From 50d4b4348e3ee8fa38ba8f864212916f77a26093 Mon Sep 17 00:00:00 2001 From: Simon Brooke Date: Sun, 2 Apr 2023 12:57:26 +0100 Subject: [PATCH] Still preparing for the big shift to property lists. --- doc/lisp1.5.md | 710 ++++++++++----------- doc/values.md | 15 +- docs/codox/beowulf.bootstrap.html | 8 +- docs/codox/beowulf.cons-cell.html | 2 +- docs/codox/beowulf.core.html | 2 +- docs/codox/beowulf.gendoc.html | 4 +- docs/codox/beowulf.host.html | 20 +- docs/codox/beowulf.io.html | 6 +- docs/codox/beowulf.manual.html | 2 +- docs/codox/beowulf.oblist.html | 2 +- docs/codox/beowulf.read.html | 2 +- docs/codox/beowulf.reader.char-reader.html | 2 +- docs/codox/beowulf.reader.generate.html | 2 +- docs/codox/beowulf.reader.macros.html | 2 +- docs/codox/beowulf.reader.parser.html | 2 +- docs/codox/beowulf.reader.simplify.html | 2 +- docs/codox/beowulf.scratch.html | 2 +- docs/codox/index.html | 2 +- docs/codox/intro.html | 6 +- docs/codox/mexpr.html | 2 +- docs/codox/values.html | 30 + resources/lisp1.5.lsp | 4 +- resources/sexpr/length.lsp | 7 +- src/beowulf/host.clj | 2 +- src/beowulf/reader/parser.clj | 32 +- test/beowulf/lisp_test.clj | 10 +- 26 files changed, 435 insertions(+), 445 deletions(-) create mode 100644 docs/codox/values.html diff --git a/doc/lisp1.5.md b/doc/lisp1.5.md index c187ba4..d554bcf 100644 --- a/doc/lisp1.5.md +++ b/doc/lisp1.5.md @@ -14,59 +14,40 @@ > Massachusetts Institute of Technology > Cambridge, Massachusetts -The Research Laboratory af Electronics is an interdepartmental -laboratory in which faculty members and graduate students from -numerous academic departments conduct research. +The Research Laboratory af Electronics is an interdepartmental laboratory in which faculty members and graduate students from numerous academic departments conduct research. -The research reported in this document was made possible in part -by support extended the Massachusetts Institute of Technology, Re- -search Laboratory of Electronics, jointly by the U.S. Army, the -U.S. Navy (Office of Naval Research), and the U.S. Air Force -(Office of Scientific Research) under Contract DA36-039-sc-78108, -Department of the Army Task 3-99-25-001-08; and in part by Con- -tract DA-SIG-36-039-61-G14; additional support was received from -the National Science Foundation (Grant G-16526) and the National -Institutes of Health (Grant MH-04737-02). +The research reported in this document was made possible in part by support extended the Massachusetts Institute of Technology, Research Laboratory of Electronics, jointly by the U.S. Army, the U.S. Navy (Office of Naval Research), and the U.S. Air Force (Office of Scientific Research) under Contract DA36-039-sc-78108, Department of the Army Task 3-99-25-001-08; and in part by Contract DA-SIG-36-039-61-G14; additional support was received from the National Science Foundation (Grant G-16526) and the National Institutes of Health (Grant MH-04737-02). -Reproduction in whole or in part is permitted for any purpose -of the United States Government. +Reproduction in whole or in part is permitted for any purpose of the United States Government. SECOND EDITION Fifteenth printing, 1985 ISBN 0 262 130 1 1 4 (paperback) +----- + #### Note regarding this Markdown document -This Markdown version of the manual was created by me, -[Simon Brooke](mailto:simon@journeyman.cc), by passing the PDF -version found at [Software Preservation](https://www.softwarepreservation.org/projects/LISP/book/LISP%201.5%20Programmers%20Manual.pdf) through a [PDF to -Markdown processor](https://pdf2md.morethan.io/), and hand-editing -the resulting document. +This Markdown version of the manual was created by me, [Simon Brooke](mailto:simon@journeyman.cc), by passing the PDF version found at [Software Preservation](https://www.softwarepreservation.org/projects/LISP/book/LISP%201.5%20Programmers%20Manual.pdf) through a [PDF to +Markdown processor](https://pdf2md.morethan.io/), and hand-editing the resulting document. -**This document is not authorised by the copyright holders.** It was -made for the purposes of study, only. +**This document is not authorised by the copyright holders.** It was made for the purposes of study, only. -Notes which I have added during editing are *NOTE: given in italics, like this*. +Generally I have tried to keep the text unaltered. Some minor headings, especially of examples, have been deliberately changed in order to aid navigation, and some apparent typographic errors have been corrected. *I have also added spaces between syntactic elements in M-expression examples to aid legibility.* Page numbers are taken from the original. Notes which I have added during editing are *NOTE: given in italics, like this*. + +----- ## PREFACE -The over-all design of the LISP Programming System is the work of John McCarthy -and is based on his paper NRecursive Functions of Symbolic Expressions and Their Com- -putation by Machinett which was published in Communications of the ACM, April 1960. +The over-all design of the LISP Programming System is the work of John McCarthy and is based on his paper "[Recursive Functions of Symbolic Expressions and Their Computation by Machine](http://www-formal.stanford.edu/jmc/recursive/recursive.html)" which was published in Communications of the ACM, April 1960. + This manual was written by Michael I. Levin. -The interpreter was programmed by Stephen B. Russell and Daniel J. Edwards. -The print and read programs were written by John McCarthy, Klim Maling, -Daniel J. Edwards, and Paul W, Abrahams. +The interpreter was programmed by Stephen B. Russell and Daniel J. Edwards. The print and read programs were written by John McCarthy, Klim Maling, Daniel J. Edwards, and Paul W, Abrahams. -The garbage collector and arithmetic features Were written by Daniel J. Edwards. -The compiler and assembler were written by Timothy P. Hart and Michael I. Levin. -An earlier compiler was written by Robert Brayton. +The garbage collector and arithmetic features Were written by Daniel J. Edwards. The compiler and assembler were written by Timothy P. Hart and Michael I. Levin. An earlier compiler was written by Robert Brayton. -The "LISP 1 Programmer's Manual" March 1, 1960, was written by Phyllis A. Fox. -Additional programs and suggestions were contributed by the following members of the Artificial Intelligence Group of the Research Laboratory of Electronics: -Marvin L. Minsky, Bertram Raphael, Louis Hodes, David M. R. Park, David C. Luckham, -Daniel G. Bobrow, James R. Slagle, and Nathaniel Rochester. +The "LISP 1 Programmer's Manual" March 1, 1960, was written by Phyllis A. Fox. Additional programs and suggestions were contributed by the following members of the Artificial Intelligence Group of the Research Laboratory of Electronics: Marvin L. Minsky, Bertram Raphael, Louis Hodes, David M. R. Park, David C. Luckham, Daniel G. Bobrow, James R. Slagle, and Nathaniel Rochester. August 17, 1962 @@ -128,39 +109,21 @@ I. LISP for SHARE Distribution ## I. THE LISP LANGUAGE -The LISP language is designed primarily for symbolic data processing. It has been -used for symbolic calculations in differential and integral calculus, electrical circuit -theory, mathematical logic, game playing, and other fields of artificial intelligence. -LISP is a formal mathematical language. It is therefore podsible to give a con- -cise yet complete description of it. Such is the purpose of this first section of the -manual. Other sections will describe ways of using LISP to advantage and will explain -extensions of the language which make it a convenient programming system. +The LISP language is designed primarily for symbolic data processing. It has been used for symbolic calculations in differential and integral calculus, electrical circuit theory, mathematical logic, game playing, and other fields of artificial intelligence. -LISP differs from most programming languages in three important ways. The -first way is in the nature of the data. In the LISP language, all data are in the form -of symbolic expressions usually referred to as S-expressions. S-expressions are of -indefinite length and have a branching tree type of structure, so that significant sub- -expressions can be readily isolated. In the LISP programming system, the bulk of -available memory is used for storing S-expressions in the form of list structures. -This type of memory organization frees the programmer from the necessity of -allocating storage for the different sections of his program. +LISP is a formal mathematical language. It is therefore possible to give a concise yet complete description of it. Such is the purpose of this first section of the manual. Other sections will describe ways of using LISP to advantage and will explain extensions of the language which make it a convenient programming system. -The second important part of the LISP language is the source language itself which -specifies in what way the S-expressions are to be processed. This consists of recur- -sive functions of S-expressions. Since the notation for the writing of recursive func- -tions of S-expressions is itself outside the S-expression notation, it will be called the -meta language. These expressions will therefore be called M-expressions. +LISP differs from most programming languages in three important ways. The first way is in the nature of the data. In the LISP language, all data are in the form of symbolic expressions usually referred to as S-expressions. S-expressions are of indefinite length and have a branching tree type of structure, so that significant sub-expressions can be readily isolated. In the LISP programming system, the bulk of available memory is used for storing S-expressions in the form of list structures. This type of memory organization frees the programmer from the necessity of allocating storage for the different sections of his program. -Third, LISP can interpret and execute programs written in the form of S- -expressions. Thus, like machine language, and unlike most other higher level languages, -it can be used to generate programs for further execution. +The second important part of the LISP language is the source language itself which specifies in what way the S-expressions are to be processed. This consists of recursive functions of S-expressions. Since the notation for the writing of recursive functions of S-expressions is itself outside the S-expression notation, it will be called the meta language. These expressions will therefore be called M-expressions. + +Third, LISP can interpret and execute programs written in the form of S-expressions. Thus, like machine language, and unlike most other higher level languages, it can be used to generate programs for further execution. ### 1.1 Symbolic Expressions The most elementary type of S-expression is the atomic symbol. -**Definition**: An atomic symbol is a string of no more than thirty numerals and capital -letters; the first character must be a letter. +**Definition**: An atomic symbol is a string of no more than thirty numerals and capital letters; the first character must be a letter. #### Examples - atomic symbols @@ -170,22 +133,15 @@ letters; the first character must be a letter. * EXTRALONGSTRINGOFLETTERS * A4B66XYZ -These symbols are called atomic because they are taken as a whole and are not -capable of being split within LISP into individual characters, Thus A, B, and AB -have no relation to each other except in so far as they are three distinct atomic -symbols. +These symbols are called atomic because they are taken as a whole and are not capable of being split within LISP into individual characters, Thus A, B, and AB have no relation to each other except in so far as they are three distinct atomic symbols. All S-expressions are built out of atomic symbols and the punctuation marks page 2 -`(` `)` and `.`. The basic operation for forming S-expressions is to combine two -of them to produce a larger one. From the two atomic symbols A1 and A2, one can -form the S-expression `(A1 . A2)`. +`(` `)` and `.`. The basic operation for forming S-expressions is to combine two of them to produce a larger one. From the two atomic symbols A1 and A2, one can form the S-expression `(A1 . A2)`. -**Definition**: An S-expression is either an atomic symbol or it is composed of these -elements in the following order: a left parenthesis, an S-expression, a dot, an S- -expression, and a right parenthesis. +**Definition**: An S-expression is either an atomic symbol or it is composed of these elements in the following order: a left parenthesis, an S-expression, a dot, an S-expression, and a right parenthesis. Notice that this definition is recursive. @@ -200,14 +156,9 @@ Notice that this definition is recursive. ### 1.2 Elementary Functions -We shall introduce some elementary functions of S-expressions. To distinguish -the functions from the S-expressions themselves, we shall write function names in -lower case letters, since atomic symbols consist of only upper case letters. Furthermore, -the arguments of functions will be grouped in square brackets rather than -parentheses. As a separator or punctuation mark we shall use the semicolon. +We shall introduce some elementary functions of S-expressions. To distinguish the functions from the S-expressions themselves, we shall write function names in lower case letters, since atomic symbols consist of only upper case letters. Furthermore, the arguments of functions will be grouped in square brackets rather than parentheses. As a separator or punctuation mark we shall use the semicolon. -The first function that we shall introduce is the function `cons`. It has two arguments -and is in fact the function that is used to build S-expressions from smaller S-expressions. +The first function that we shall introduce is the function `cons`. It has two arguments and is in fact the function that is used to build S-expressions from smaller S-expressions. #### Examples - the cons function @@ -217,13 +168,11 @@ cons[(A . B); C] = ((A . B) . C) cons[cons[A; B]; C] = ((A . B) . C) ``` -The last example is an instance of composition of functions. It is possible to build -any S-expression from its atomic components by compositions of the function cons. -The next pair of functions do just the opposite of cons. They produce the subexpres- -sions of a given expression. +The last example is an instance of composition of functions. It is possible to build any S-expression from its atomic components by compositions of the function cons. The next pair of functions do just the opposite of cons. They produce the subexpressions of a given expression. -The function `car` has one argument. Its value is the first part of its composite -argument. `car` of an atomic symbol is undefined. +The function `car` has one argument. Its value is the first part of its composite argument. `car` of an atomic symbol is undefined. + +*Note that where this says 'car of an atomic symbol is undefined', it seems to mean it literally. There seems to have been no mechanism for distinguishing cons cells from other items in memory, so that the car of, for example, a decimal number could be taken, although the result #### Examples - the car function @@ -284,13 +233,14 @@ eq[A; A] = T eq[A; B] = F eq[A; (A . B)] is undefined eq[(A . B);(A . B)] is undefined +``` The predicate `atom` is true if its argument is an atomic symbol, and false if its argument is composite. #### Examples - atom -```` +``` atom[EXTRALONGSTRINGOFLETTERS] = T atom[(u . v)] = F atom[car[(u . v)]] = T @@ -300,25 +250,17 @@ atom[car[(u . v)]] = T ### 1.3 List Notation -The S-expressions that have been used heretofore have been written in dot notation. -It is usually more convenient to be able to write lists of expressions of indefinite length, -such as `(A B C D E)`. +The S-expressions that have been used heretofore have been written in dot notation. It is usually more convenient to be able to write lists of expressions of indefinite length, such as `(A B C D E)`. -Any S-expression can be expressed in terms of the dot notation. However, LISP has an -alternative form of S-expression called the list notation. The list `(m1 m2... mn)` can be -defined in terms of dot notation. It is identical to `(m1 . (m2 . (... . (mn . NIL)... )))`. +Any S-expression can be expressed in terms of the dot notation. However, LISP has an alternative form of S-expression called the list notation. The list `(m1 m2... mn)` can be defined in terms of dot notation. It is identical to `(m1 . (m2 . (... . (mn . NIL)... )))`. -The atomic symbol NIL serves as a terminator for lists. The null list `()` is iden- -tical to `NIL`. Lists may have sublists. The dot notation and the list notation may be -used in the same S-expression, +The atomic symbol NIL serves as a terminator for lists. The null list `()` is identical to `NIL`. Lists may have sublists. The dot notation and the list notation may be used in the same S-expression, -Historically, the separator for elements of lists was the comma `(,)`; however, the -blank is now generally used. The two are entirely equivalent in LISP. `(A, B, C)` is -identical to `(A B C)`. +Historically, the separator for elements of lists was the comma `(,)`; however, the blank is now generally used. The two are entirely equivalent in LISP. `(A, B, C)` is identical to `(A B C)`. #### Examples - list notation -``` +```lisp (A B C) = (A . (B . (C . NIL))) ((A B) C) = ((A . (B . NIL)) . (C . NIL)) (A B (C D)) = (A . (B . ((C . (D . NIL)). NIL))) @@ -327,9 +269,7 @@ identical to `(A B C)`. (A (B . C)) = (A . ((B . C) . NIL)) ``` -It Is important to become familiar with the results of elementary functions on -S-expressions written in list notation. These can always be determined by translating -into dot notation. +It Is important to become familiar with the results of elementary functions on S-expressions written in list notation. These can always be determined by translating into dot notation. #### Examples - list notation 2 @@ -342,300 +282,296 @@ cdr[(A)] = NIL car[cdr[(A B C)]] = B ``` -It is convenient to abbreviate multiple `car`s and `cdr`s. This is done by forming -function names that begin with `c`, end with `r`, and have several `a`s and `d`s between -them. +It is convenient to abbreviate multiple `car`s and `cdr`s. This is done by forming function names that begin with `c`, end with `r`, and have several `a`s and `d`s between them. -### Examples - composed accessor functions +#### Examples - composed accessor functions ``` cadr[(A B C)] = car[cdr[(A B C)]] = B -caddr[(A B C )] = C +caddr[(A B C)] = C cadadr[(A (B C) D)] = C ``` -The last a or d in the name actually signifies the first operation in order to be +page 5 + +The last `a` or `d` in the name actually signifies the first operation in order to be performed, since it is nearest to the argument. -1.4 The LISP Meta-language -We have introduced a type of data called S-expressions, and five elementary func- -tions of S-expressions. We have also discussed the following features of the meta- -language. +### 1.4 The LISP Meta-language -1. Function names and variable names are like atortlfc symbols except that they -use lower case letters. -2. The arguments of a function are bound by square brackets and separated from -each other by semicolons. -3. Compositions of functions may be written by using nested sets of brackets. -These rules allow one to write function definitions such as -third[x]=car[cdr[cdr[x]]]. +We have introduced a type of data called S-expressions, and five elementary functions of S-expressions. We have also discussed the following features of the meta-language. -This function selects the third item on a list. For example, +1. Function names and variable names are like atomic symbols except that they use lower case letters. +2. The arguments of a function are bound by square brackets and separated from each other by semicolons. +3. Compositions of functions may be written by using nested sets of brackets. These rules allow one to write function definitions such as `third[x]=car[cdr[cdr[x]]]`. -third is actually the same function as caddr. -The class of functions that can be formed in this way is quite limited and hot Very -interesting. A much larger class of functions can be defined by means of the con- -ditional expression, a device for providing branches in function definitions. -A conditional expression has the following form: +This function selects the third item on a list. For example, `third` is actually the same function as `caddr`. -``` -where each pi is an expression whose value may be truth or falsity, and each ei is -any expression. The meaning of a conditional expression is: if pl is true. then the -value of el is the value of the entire expression. If pl is false, then if p2 is true -the value of e2 is the value of the entire expression. The pi are searched from left -to right until the first true one is found. Then the corresponding ei is selected. If -none of the pi are true, then the value of the entire expression is undefined. -Each pi or ei can itselk be either an 6-expression, a function, ta composition of -functions or may it self be another conditional expression. -Example -[eq[car[x];~]eons[~ ;cdr[x]]; T-x] -The atomic symbol T represents truth, The value of this expression is obtained -if one replaces car of x by B if it happens to be A, but leaving x unchanged if car of +The class of functions that can be formed in this way is quite limited and not very interesting. A much larger class of functions can be defined by means of the conditional expression, a device for providing branches in function definitions. A conditional expression has the following form: + +> where each pi is an expression whose value may be truth or falsity, and each ei is +> any expression. The meaning of a conditional expression is: if p1 is true. then the +> value of e1 is the value of the entire expression. If p1 is false, then if p2 is true +> the value of e2 is the value of the entire expression. The pi are searched from left +> to right until the first true one is found. Then the corresponding ei is selected. If +> none of the pi are true, then the value of the entire expression is undefined. +> +> Each pi or ei can itself be either an S-expression, a function, a composition of +> functions or may itself be another conditional expression. + +#### Example - conditional expression + +`[eq[car[x]; A] -> cons[B; cdr[x]]; T -> x]` + +The atomic symbol `T` represents truth. The value of this expression is obtained +if one replaces `car` of `x` by B if it happens to be A, but leaving `x` unchanged if `car` of it is not A. -``` -``` +page 6 + The main application of conditional expressions is in defining functions recursively. -``` -Example +#### Example +`ff[x] = [atom[x] -> x; T -> ff[car[x]]]` + +This example defines the function `ff` which selects the first atomic symbol of any +given expression. This expression can be read: If `x` is an atomic symbol, then `x` +itself is the answer. Otherwise the function `ff` is to be applied to car of `x`. + +If `x` is atomic, then the first branch which is `x` will be selected. Otherwise, the +second branch `ff[car[x]]` will be selected, since `T` is always true. + +The definition of `ff` is recursive in that `ff` is actually defined in terms of itself. If +one keeps taking `car` of any S-expression, one will eventually produce an atomic symbol; therefore the process is always well defined. + +Some recursive functions may be well defined for certain arguments only, but infinitely recursive for certain other arguments. When such a function is interpreted in the LISP programming system, it will either use up all of the available memory, or loop until the program is halted artificially. + +We shall now work out the evaluation of `ff[((A. B). C)]`. First, we substitute the +arguments in place of the variable `x` in the definition and obtain ``` -ff[x]=[atom[x]-x; T-ff[car[x]]] -This example defines the function ff which selects the first atomic symbol of any -given expression. This expression can be read: If x is an atomic symbol, then x -itself is the answer. Otherwise the function ff is to be applied to car of x. -If x is atomic, then the first branch which is x l1 will be selected. Otherwise, the -second branch nff[car[x]]n will be selected, since T is always true. -The definition of ff is recursive in that ff is actually deefined in terms of itself. If -one keeps taking cay of any S-expression, one will eventually produce an atomic sym- -bol; therefore the process is always well defined. -Some recursive functions may be well defined for certain arguments only, but in- -finitely recursive for certain other arguments. When such a function is interpreted in -the LISP programming system, it will either use up all of the available memory, or -loop until the program is halted artificially. -We shall now work out the evaluation of ff[((A. B). c)]. First, we substitute the -arguments in place of the variable x in the definition and obtain -ff[((~. B). C)]=[atom[((A. B). c)]-((A. B). C); T-ff[car[((A. B). c)]]] -but ((A. B). C) is not atomic, and so we have -= [T-ff [car [((A. B). C )]]I -= ff[car[((A. B). c)]] -= ff[(~. B)] -At this point, the definition of ff must be used recursively. Substituting (A. B) -for x gives -= [atom[(A. B)]-(A. B); Tdff[car[(A. B)]]] -= [T-ff[car[(~. B)]]] -= ff[car[(A. B)]] +ff[((A . B) . C)]=[atom[((A . B) . C)]->((A . B) . C); T->ff[car[((A . B) . C)]]] +``` +but `((A. B). C)` is not atomic, and so we have +``` += [T->ff [car[((A . B) . C)]] += ff[car[((A . B) . C)]] += ff[(A . B)] +``` +At this point, the definition of ff must be used recursively. Substituting `(A . B)` +for `x` gives +``` += [atom[(A . B)] -> (A . B); T -> ff[car[(A . B)]]] += [T -> ff[car[(A . B)]]] += ff[car[(A . B)]] = ff[A] -= [atom[A]-A; T-ff [car [A 111 += [atom[A] -> A; T -> ff[car[A]]] += A ``` +The conditional expression is useful for defining numerical computations, as well as computations with S-expressions. The absolute value of a number can be defined by ``` -The conditional expression is useful for defining numerical computations, as well -as computations with S-expressions. The absolute value of a number can be defined by -``` - +|x| = [x<0 -> -x; T -> x] ``` The factorial of a nonhnegative integer can be defined by -n! =[n=0-1; T-n-[n-l]! 3 -This recursive definition does not terminate for negative arguments. A function that ``` +n! = [n=0 -> 1; T -> n.[n-l]!] +``` +This recursive definition does not terminate for negative arguments. A function that + +page 7 is defined only for certain arguments is called a partial function. -The Euclidean algorithm for finding the greatest common divisor of two positive -integers can be defined by using conditional expressions as follows: -rem[u;vi is the remainder when u is divided by 2 -A detailed discussion of the theory of functions defined recursively by conditional -expressions is found in A Basis for a Mathematical Theory of Computation " by -J. McCarthy, Proceedings of the Western Joint Computer Conference, May 1961 -(published by the Institute of Radio Engineers). -It is usual for most mathematicians-exclusive of those devoted to logic-to use the -word function imprecisely, and to apply it to forms such as JI^2 ts Because we -shall later compute with expressions that stand for functions, we need a notation that -expresses the distinction between functions and forms. The notation that we shall use -is the lambda notation of Alonzo Church.^1 -Let be an expression that stands for a function of two integer variables. It -should make sense to write f[3;4] and to be able to determine the value of this expres- -sion. For example, sum[3;4]=7. The expression y^2 tx does not meet this requirement. -It is not at all clear whether the value of y^2 +x[3;41 is 13 or 19. An expression such as -y^2 tx will be called a form rather than a function. A form can be converted to a func- -tion by specifying the correspondence between the variables in the form and the argu- -ments of the desired function. -If E is a form in the variables x l;.. .;xn, then the expression h[[x l;.. .;xn]; € -represents the function of n variables obtained by substituting the n arguments in -order for the variables xl;. .;xn, respectively. For example, the function ~[[x;~]; -y^2 tx] is a function of two variables, and )i[[x;y);y2+x1[3;4]=4^2 +3=19. ~[L~;xJY~+~I[~;~I -=3^2 +4=13. -The variables in a lambda expression are dummy or bound variables because sys- -tematically changing them does not alter the meaning of the expression. Thus X[[u;vk -v^2 tu] means the same thing as A[[X;~~~^2 tx]. -We shall sometimes use expressions in which a variable is not bound by a lambda. -For example, in the function of two variables )i[[x;y~xntyn] the variable n is not -bound. This is called a free variable. It may be regarded as a parameter. Unless -n has been given a value before trying to compute with this function, the value of the -function must be undefined. +The Euclidean algorithm for finding the greatest common divisor of two positive integers can be defined by using conditional expressions as follows: -1. A. Church, The Calculi of Lambda-Conversion (Princeton University Press, - Princeton, New Jersey, 194r +``` +gcd[x; y]=[x>y -> gcd[y; x]; + rem[y;x]=0 -> x] +``` -The lambda notation alone is inadequate for naming recursive functions. Not only -must the variables be bound, but the name of the function must be bound, since it is -used inside an expression to stand for the entire expression. The function ff was -previously defined by the identity +`rem[u; v]` is the remainder when `u` is divided by `v`. + +A detailed discussion of the theory of functions defined recursively by conditional expressions is found in [A Basis for a Mathematical Theory of Computation](http://jmc.stanford.edu/articles/basis/basis.pdf) by J. McCarthy, Proceedings of the Western Joint Computer Conference, May 1961 (published by the Institute of Radio Engineers). + +It is usual for most mathematicians -- exclusive of those devoted to logic -- to use the word 'function' imprecisely, and to apply it to forms such as y2+x. Because we shall later compute with expressions that stand for functions, we need a notation that expresses the distinction between functions and forms. The notation that we shall use is the [lambda notation of Alonzo Church](https://compcalc.github.io/public/church/church_calculi_1941.pdf). + +Let `f`be an expression that stands for a function of two integer variables. It +should make sense to write `f[3; 4]` and to be able to determine the value of this expres- +sion. For example, `sum[3; 4] = 7`. The expression y2 + x does not meet this requirement. +It is not at all clear whether the value of y2 + x[3; 4] is 13 or 19. An expression such as +y2 + x will be called a form rather than a function. A form can be converted to a function by specifying the correspondence between the variables in the form and the arguments of the desired function. + +If ε is a form in the variables x1;... ;xn, then the expression λ[[x1;... ;xn]ε] represents the function of n variables obtained by substituting the n arguments in order for the variables x1;... ;xn, respectively. For example, the function λ[[x; y]; y2 + x] is a function of two variables, and λ[[x; y]; y2 + x][3; 4] =42 + 3 = 19. λ[[x; y]; y2 + x][4; 3] = 32 + 4 = 13. + +*TODO: detail formatting in the above paragraph is still slightly wrong.* + +The variables in a lambda expression are dummy or bound variables because systematically changing them does not alter the meaning of the expression. Thus λ[[u; v]; u2 + v] means the same thing as λ[[x; y]; y2 + x]. + +We shall sometimes use expressions in which a variable is not bound by a lambda. For example, in the function of two variables λ[[x; y]; xn + yn] the variable `n` is not bound. This is called a free variable. It may be regarded as a parameter. Unless `n` has been given a value before trying to compute with this function, the value of the function must be undefined. + +page 8 + +The lambda notation alone is inadequate for naming recursive functions. Not only must the variables be bound, but the name of the function must be bound, since it is used inside an expression to stand for the entire expression. The function `ff` was previously defined by the identity + +`ff[x] = [atom[x] -> x; T -> ff[car[x]]]` Using the lambda notation, we can write -ff=h[[xh [atorn[x]-x; T-ff [car [x]]j) -The equality sigq in these identities is actually not part of the LISP meta-language -and is only a orutch until we develop the correct notation. The right side of the last -equation cannot serve as an expression for the function &because there is nothing to -indicate that the occurrence of ff inside it stands for the function that is being defined. + +`ff =` λ`[x] = [atom[x] -> x; T -> ff[car[x]]]` + +The equality sign in these identities is actually not part of the LISP meta-languageand is only a crutch until we develop the correct notation. The right side of the last equation cannot serve as an expression for the function `ff` because there is nothing to indicate that the occurrence of `ff` inside it stands for the function that is being defined. + In order to be able to write expressions that bear their own name, we introduce -the label notatioe. If E is an expression, and o is its name, we write label[a;~]. -The function 3 can now be written without an equal sign: +the label notation. If ε is an expression, and α is its name, we write label[α; ε]. -In this expression, is a bound variable, and ff is a bound function name. +The function `ff` can now be written without an equal sign: -1.5 Syntactic $ummaryl -All parts of the LISP language have now been explained. That which follows is a -complete gyntactic definition of the LISP language, together with semantic comments. -The definition is given in Backus notation2 with the addition of three dots(.. .) to avoid -naming unneccessary syntactic types. -In Backus notation the symbols I1::=l1, I1", and It I fl are used. The rule -::= I (. ) means that -an $-expression is either an atomic symbol, or it is a left parenthesis followed by an -S-expression followed by a dot followed by an S-expression followed by a right paren- -thesis. The vertical bar means or " , and the angular brackets always enclose ele- -ments of the syntax that is being defined. -The Data Language -CLETTER>::~AIB cI... IZ +`label[ff =` λ`[[x]; [atom[x] -> x; T -> ff[car[x]]]]` -## ::=0I112 I .,. ( +In this expression, `x` is a bound variable, and `ff` is a bound function name. -``` -c atomic-symbol >::= -::= I I -Atomic symbols are the smallest entities in LISP. Their decomposition into char- -acter s has no significance. +### 1.5 Syntactic Summary + +[This section is for completeness and may be skipped upon first reading.] + +All parts of the LISP language have now been explained. That which follows is a complete syntactic definition of the LISP language, together with semantic comments. The definition is given in [Backus notation](https://www.softwarepreservation.org/projects/ALGOL/paper/Backus-ICIP-1959.pdf) with the addition of three dots(...) to avoid naming unnecessary syntactic types. + +In Backus notation the symbols `::=`, `<`, `>`, and `|` are used. The rule + +```BNF + ::= | ( . ) ``` -1. This election is for completeness and may be skipped upon first reading. -2. J. W. Backus, The Syntax and Semantics of the Proposed International Algebraic -Language of the Zurich ACM-Gamm Conference. ICIP Paris, June 1959. +means that an S-expression is either an atomic symbol, or it is a left parenthesis followed by an S-expression followed by a dot followed by an S-expression followed by a right parenthesis. The vertical bar means "or" , and the angular brackets always enclose elements of the syntax that is being defined. -< S-expression >:: = ( -(. ) I -(. ,. ) -When three dots are used in this manner, they mean that any number of the given -type of symbol may occur, including none at all. According to this rule, ( ) is a valid -S-expression. (It is equivalent to NIL. ) -The dot notation is the fundamental notation of S-expressions, although the list -notation is often more convenient. Any Sdexpression can be written in dot notation. -The Meta-Language -::=alb(cl... (z -::= -::= I I -The names of functions and variables are fornied in the same manner as atomic -symbols but with lower -case letters. +#### The Data Language +```BNF + ::= A|B|C| ... |Z + ::= 0|1|2| ... |9 + ::= + ::= | | ``` -A form is an expression that can be evaluated. A form that is merely a constant -has that constant as its value. If a form is a variable, then the value of the form is -the S-expression that is bound to that variable at the time when we evaluate the form, -The third part of this rule states that we may write a function followed by a list of -arguments separated by semicolons and enclosed in square brackets. The expressions -for the arguments are themselves forms; this indicates that cornpasitions of functions -are permitted. -The last part of this rule gives the format of the conditional expression. This is -evaluated by evaluating the forms in the propositional position in order until one is -found whose value is T. Then the form after the arrow is evaluated and give$ the -value of the entire expression. -::= ( -k[;
] I -label[< identifier >; ] -:: =[;... ; ] -A function can be simply a name. In this case its meaning must be previously -understood. A function may be defined by using the lambda notation and establishing -a correspondence between the arguments and the variables used in a form. If the -function is recursive, it must be given a name by using a label. +Atomic symbols are the smallest entities in LISP. Their decomposition into characters has no significance. + +page 9 + +```BNF + ::= | + ( . ) | + ( ... ) +``` +When three dots are used in this manner, they mean that any number of the given type of symbol may occur, including none at all. According to this rule, `( )` is a valid S-expression. (It is equivalent to `NIL`. ) + +The dot notation is the fundamental notation of S-expressions, although the list notation is often more convenient. Any S-expression can be written in dot notation. + +#### The Meta-Language + +```BNF + ::= a|b|c| ... |z + ::= + ::= | | +``` +The names of functions and variables are fornied in the same manner as atomic symbols but with lower-case letters. + +```BNF + ::= | + | + [ ... ] | + [ -> ; ... ; -> ] + ::= + ::= + ::= + ``` -1.6 A Universal LISP Function -An interpreter or universal function is one that can compute the value of any given -function applied to its arguments when given a description of that function. (Of course, -if the function that is being interpreted has infinite recursion, the interpreter will -recur infinitely also. ) -We are now in a position to define the universal LISP function evalquote[fn;args], -When evalquote is given a function and a list of arguments for that function, it computes -the value of the function applied to the arguments. -LISP functions have S-expressions as arguments. In particular, the argument -"fn" of the function evalquote must be an S-expression. Since we have been writing -functions as M-expressions, it is necessary to translate them into S-expressions. -The following rules define a method of translating functions written in the meta- -language into S-expressions. +A form is an expression that can be evaluated. A form that is merely a constant has that constant *[sic]* as its value. If a form is a variable, then the value of the form is the S-expression that is bound to that variable at the time when we evaluate the form, + +The third part of this rule states that we may write a function followed by a list of arguments separated by semicolons and enclosed in square brackets. The expressions for the arguments are themselves forms; this indicates that compositions of functions are permitted. + +The last part of this rule gives the format of the conditional expression. This is evaluated by evaluating the forms in the propositional position in order until one is found whose value is `T`. Then the form after the arrow is evaluated and gives the value of the entire expression. + +`::= |` λ`[;] | label[; ]` + +` ::= [; ... ; ]` + +A function can be simply a name. In this case its meaning must be previously understood. A function may be defined by using the lambda notation and establishing a correspondence between the arguments and the variables used in a form. If the function is recursive, it must be given a name by using a label. + +page 10 + +### 1.6 A Universal LISP Function +An interpreter or universal function is one that can compute the value of any given function applied to its arguments when given a description of that function. (Of course, if the function that is being interpreted has infinite recursion, the interpreter will recur infinitely also. ) + +We are now in a position to define the universal LISP function `evalquote[fn;args]`. When `evalquote` is given a function and a list of arguments for that function, it computes the value of the function applied to the arguments. + +LISP functions have S-expressions as arguments. In particular, the argument `fn` of the function `evalquote` must be an S-expression. Since we have been writing functions as M-expressions, it is necessary to translate them into S-expressions. + +The following rules define a method of translating functions written in the meta-language into S-expressions. + +1. If the function is represented by its name, it is translated by changing all of the letters to upper case, making it an atomic symbol. Thus `car` is translated to `CAR`. + +2. If the function uses the lambda notation, then the expression λ`[x1; ...; xn]`ε`]` is translated into (LAMBDA (X1... XN) ε*), where ε* is the translation of ε. +3. If the function begins with label, then the translation of label[α; ε] is (LABEL + α* ε*). -1. If the function is represented by its name, it is translated by changing -all of the letters to upper case, making it an atomic symbol. Thus is translated -to CAR. -2. If the function uses the lambda notation, then the expression k[[x. .;xn]; 1 -is translated into (LAMBDA (X1... XN) e*), where E* is the translation of c. -3. If the function begins with label, then the translation of label[= ;€I is (LABEL -a*e*). Forms are translated as follows: -1. A variable, like a function name, is translated by using uppercase letters. -Thus the translation of varl is VAR1. -2. The obvious translation of letting a constant translate into itself will not work. -Since the translation of is X, the translation of X must be something else to avoid -ambiguity. The solution is to quote it. Thus X is translated into (QUOTE X). -3. The form fn[argl;.. .;atgn] is translated into (fn*argl*... argn*) -4. The conditional expression [Pl-el;.. .; pn-en] is translated into (COND - * * -``` -Examples -M-expressions S -expressions -X X -car CAR -car [x] (CAR X) -T (QUOTE T) -ff [car [XI] (FF (CAR X)) -[atom[x]-x; T-ff [car [x]]] (COND ((ATOM X) X) -((QUOTE T) (FF (CAR X)))) -label[ff ;h[[x];[atom[x]-x; T-ff[car [XI]]]] (LABEL FF (LAMBDA (X) (COND -((ATOM X) X) -((QUOTE T) (FF (CAR X)))))) -``` +1. A variable, like a function name, is translated by using uppercase letters. Thus the translation of `var1` is `VAR1`. + +2. The obvious translation of letting a constant translate into itself will not work. Since the translation `x` of is `X`, the translation of `X` must be something else to avoid ambiguity. The solution is to quote it. Thus `X` is translated into `(QUOTE X)`. + +3. The form `fn[arg`1`; ... ;arg`n`]` is translated into `(fn* arg`1* `... arg`n*`)`. + +4. The conditional expression [p1 -> e1; ... ; pn -> en] is translated into + + (COND (p1* e1*) ... (pn* en*)) + +#### Examples - translation, M-expressions to S-expressions + +| M-expressions | S -expressions | +| ---- | ---- | +| X | X | +| car | CAR | +| car[x] | (CAR X) | +| T | (QUOTE T) | +| ff[car[X]] | (FF (CAR X)) | +| [atom[x]-x; T-ff [car [x]]] | (COND ((ATOM X) X) ((QUOTE T) (FF (CAR X)))) | +| label[ff ;h[[x];[atom[x]-x; T-ff[car [X]]]] | (LABEL FF (LAMBDA (X) (COND ((ATOM X) X) ((QUOTE T) (FF (CAR X)))))) | -``` Some useful functions for handling S-expressions are given below. Some of them -``` -are needed as auxiliary functions for evalquote. +page 11 + +are needed as auxiliary functions for `evalquote`. + +`equal[x;y]` -equal[x;y] This is a predicate that is true if its two arguments are identical S-expressions, and is false if they are different. (The elementary predicate - eq is defined only for -atomic arguments. ) The definition of egual is an example of a conditional expression +atomic arguments. ) The definition of equal is an example of a conditional expression inside a conditional expression. ``` -equal[x; y]=[atom[x] atom[^] -eq[x;~]; T-F]; -equal[car [x]; car [Y]]-equal[cdr [x]; cdr [y]]; -T-F] +equal[x; y]=[atom[x] -> [atom[y] -> eq[x; y]; T -> F]; + equal[car[x]; car[y]] -> equal[cdr[x]; cdr[y]]; + T -> F] ``` This can be translated into the following S-expression: , -``` -(LABEL EQUAL (LAMBDA (X Y) (COND -((ATOM X) (COND ((ATOM Y) (EQ X Y)) ((QUOTE T) (QUOTE F)))) -((EQUAL (CAR X) (CAR Y)) (EQUAL (CDR X) (CDR Y))) -((QUOTET)(QUOTEF)) )I) +```lisp +(LABEL EQUAL + (LAMBDA (X Y) + (COND ((ATOM X) (COND ((ATOM Y) (EQ X Y)) + ((QUOTE T) (QUOTE F)))) + ((EQUAL (CAR X) (CAR Y)) (EQUAL (CDR X) (CDR Y))) + ((QUOTE T)(QUOTE F))))) ``` - sub st[^;^; z] This function gives the result of substituting the S-expression x for all occurrences -of the atomic symbol y in the S-expression z. It is defined by + of the atomic symbol y in the S-expression z. It is defined by ###### s~bst[x;~;z] = [eq~al[~;z] -- x;atom[z] - z;T - cons[subst @@ -933,7 +869,7 @@ Section I. ) eval will evaluate the variables and give it to cons. cons[^;^] = (A. B) The actual interpreter skips one step required by the universal function, namely, -apply[~O~~;(A B);((X. A) (Y. B))]. + apply[~O~~;(A B);((X. A) (Y. B))]. 2.2 Constants It is sometimes assumed that a constant stands for itself as opposed to a variable @@ -990,8 +926,8 @@ three ways in which a subroutine can be present in the system. 2. The function is hand-coded by the user in the assembly type language, LAP. 3. The function is first defined by an S-expression, and then compiled by the LISP -compiler. Compiled functions run from 10 to 100 times as fast as they do when they -are interpreted. + compiler. Compiled functions run from 10 to 100 times as fast as they do when they + are interpreted. ``` 2.5 Special Forms @@ -1309,9 +1245,9 @@ difference[^;^] has for its value the algebraic difference of its arguments. * minus[x] has for its value -x. times[xl;.. .;xn] is a function of any number of arguments, whose value is the product -(with correct sign) of its arguments. -addl[x] has xtl for its value. The value is fixed-point or floating-point, depending -on the argument. + (with correct sign) of its arguments. + addl[x] has xtl for its value. The value is fixed-point or floating-point, depending + on the argument. * subl[x] has x-1 for its value. The value is fixed-point or floating-point, depending on the argument. * max[xl;... ;xn] chooses the largest of its arguments for its value. Note that @@ -1429,13 +1365,13 @@ Length is a function of one argurnentL. The program uses two program variables by the program. In English the program is written: This is a function of one argument 1. It is a program with two program variables 2 and 1. -Store 0 in -Store the argument 1 in 2. -A If g contains NIL, then the program is finished, -and the value is whatever is now in 2. -Store in u, cdr of what is now in g. -Store in 1, one more than what is now in -Go to A. + Store 0 in + Store the argument 1 in 2. + A If g contains NIL, then the program is finished, + and the value is whatever is now in 2. + Store in u, cdr of what is now in g. + Store in 1, one more than what is now in + Go to A. ``` We now write this program as an M-expression, with a few new notations. This @@ -1541,11 +1477,11 @@ the TEST by reading in a core memory image from the temporary tape. thesis will cause a read error and terminate reading. A complete card deck for a LISP run might consist of: a: LISP loader -b: ID card (Optional) -c: Several Packets -.d: FIN card -e: Two blank cards to prevent card reader from hanging up -The ID card may have any information desired by the computation center. It will be + b: ID card (Optional) + c: Several Packets + .d: FIN card + e: Two blank cards to prevent card reader from hanging up + The ID card may have any information desired by the computation center. It will be printed at the head of the output. @@ -1704,9 +1640,9 @@ the garbage collector. 7. 1 Representation of List Structure Lists are not stored in the computer as sequences of BCD characters, but as struc- -tural forms built out of computer words as parts of trees. + tural forms built out of computer words as parts of trees. In representing list structure, a computer word will be depicted as a rectangle -divided into two sections, the address and decrement. + divided into two sections, the address and decrement. add. I dec. @@ -2729,7 +2665,7 @@ es[x;y - I SUBR predicate CLA TRA TRUE OCT -X PZE + X PZE ``` X @@ -2793,8 +2729,8 @@ respectively. - 0r[x1;x2... ;xn] : FSUBR predicate The arguments of or are evaluated in sequence from left to right, until one is found -that is true, or until the end of the list is reached. The value of 2 is true or -false respectively. + that is true, or until the end of the list is reached. The value of 2 is true or + false respectively. * not [x] SUBR predicate The value of not is true if its argument is false, and false otherwise. @@ -2844,8 +2780,8 @@ erty list for FF. - pr~p[x;~;u] SUBR functional The function prop - searches the list x for an item that is - eq to y. If such an element -is found, the value of prop is the rest of the list beginning immediately after the element. -Otherwise the value is u[ 1, where 2 is a function of no arguments. + is found, the value of prop is the rest of the list beginning immediately after the element. + Otherwise the value is u[ 1, where 2 is a function of no arguments. ##### prop[^;^; u] = [null[x] - u[ ];eq[car[x];y] -cdr[x] @@ -2905,11 +2841,11 @@ Table Buildinrr and Table Reference Functions - pair [x; y] SUBR The function pair has as value the list of pairs of corresponding elements of the lists -x and y. The arguments x and y must be lists of the same number of elements. They -should & be atomic symbols. The value is a dotted pair list, i. e. ((a (a p2)... -pair[x;y] = [prog[u;v; m] -u:= x; -v:= y; + x and y. The arguments x and y must be lists of the same number of elements. They + should & be atomic symbols. The value is a dotted pair list, i. e. ((a (a p2)... + pair[x;y] = [prog[u;v; m] + u:= x; + v:= y; #### A [null[u] - [null[v] - return[m];~ - error[$2]]] @@ -2972,8 +2908,8 @@ nconc does not copy its first argument. * conc[xl;x2;... ;x n ] : FEXPR pseudo-function * conc concatenates its arguments by stringing them all together on the top level. For -example, -conc[(~ (B C) D); (F); (G H)] = (A (B C) D F G H). + example, + conc[(~ (B C) D); (F); (G H)] = (A (B C) D F G H). * conc concatenates its arguments without copying them. Thus it changes existing list structure and is a pseudo-function. The value of conc is the resulting concatenated list. @@ -3079,9 +3015,9 @@ go[~oopl1 - sear~h[x;~;f;u] : SUBR functional The function search looks through a list x for an element that has the property p, -and if such an element is found the function f of that element is the value of search. -If there is no such element, the function u of one argument x is taken as the value of -search (in this case x is, of course, NIL). + and if such an element is found the function f of that element is the value of search. + If there is no such element, the function u of one argument x is taken as the value of + search (in this case x is, of course, NIL). ``` Arithmetic Functions @@ -3258,11 +3194,11 @@ reader. The list that is read is the value of read. - print [x] SUBR pseudo-function The execution of - print causes the S-expression x to be printed on SYSPOT and/or -the on-line printer. The value of print is its argument. -punchrx] - SUBR pseudo.-function -The execution of punch causes S-expression x to be punched in BCD card images -on SYSPPT. The value of punch - is its argument. -prin l [x] SUBR pseudo-function + the on-line printer. The value of print is its argument. + punchrx] - SUBR pseudo.-function + The execution of punch causes S-expression x to be punched in BCD card images + on SYSPPT. The value of punch - is its argument. + prin l [x] SUBR pseudo-function * prinl prints an atomic symbol without terminating the print line. The argument of - prini must be an atomic symbol. @@ -4281,7 +4217,7 @@ The character-packing functions are: 1. pack [c] - : SUBR pseudo-function The argument of packmust be a character object. - pack adds the character -c at the end of the sequence of characters in BOFFO. The value of pack - is NIL. + c at the end of the sequence of characters in BOFFO. The value of pack - is NIL. 2. clearbuff [ ] SUBR pseudo -func tion clearbuff is a function of no arguments. It clears BOFFO and has value NIL. The contents of BOFFO are undefined until a clearbuff has been performed. @@ -4293,13 +4229,13 @@ BOFFO is automatically cleared. Note that intern [mknam[ ]I yields the object whose print name is in BOFFO. 4. numob [ ] ' SUBR pseudo -function numob is a function of no arguments. Its value is the numerical object repre- -sented by the sequence of characters in BOFFO. (Positive decimal integers from -0 to 9 are converted so as to point to the corresponding character object. ) + sented by the sequence of characters in BOFFO. (Positive decimal integers from + 0 to 9 are converted so as to point to the corresponding character object. ) 5. unpack [x]: SUBR pseudo-function This function has as argument a pointer to a full word. unpack considers -the full word to be a set of 6 BCD characters, and has as value a list of these -char act er s ignoring all characters including and following the first 77. + the full word to be a set of 6 BCD characters, and has as value a list of these + char act er s ignoring all characters including and following the first 77. 6. h~tern[~name] : SUBR pseudo-function This function has as argument a pointer to a PNAME type structure such as - @@ -4338,7 +4274,7 @@ CURCHAR. There are three functions which affect the value of CURCHAR: 1. startread [ 1: : SUBR ps eudo-function startread is a function of no arguments which causes a new card to be read. -The value of startread is the first character on that card, or more precisely, + The value of startread is the first character on that card, or more precisely, ``` the object corresponding to the first character on the card. If an end-of-file @@ -4351,20 +4287,20 @@ completely read. 2. advance [ 1: SUBR pseudo -function advance is a function of no arguments which causes the next character to be -read. The value of advance is that character. After the 72nd character on the -card has been read, the next advance will have value $EOR$. After reading -$EOR$, the next advance will act like a startread, i. e., will read the first char- -acter of the next card unless an end-of-file condition exists. The new value of -CURCHAR is the same as the output of advance; executing advance also increases -the value of CHARCOUNT by 1. However, CHARCOUNT is undefined when -CURCHAR is either $EOR $ or $EOF $. + read. The value of advance is that character. After the 72nd character on the + card has been read, the next advance will have value $EOR$. After reading + $EOR$, the next advance will act like a startread, i. e., will read the first char- + acter of the next card unless an end-of-file condition exists. The new value of + CURCHAR is the same as the output of advance; executing advance also increases + the value of CHARCOUNT by 1. However, CHARCOUNT is undefined when + CURCHAR is either $EOR $ or $EOF $. 3. endread [ 1: SUBR pseudo-function endread is a function of no arguments which causes the remainder of the -card to be read and ignored. endread sets CURCHAR to $EOR$ and leaves -CHARCOUNT undefined; the value of endread is always $EOR $. An advance -following endread acts like a startread. If CURCHAR already has value $EOR $ -and endread is performed, CURCHAR will remain the same and endread will, -as usual, have value $EOR $. + card to be read and ignored. endread sets CURCHAR to $EOR$ and leaves + CHARCOUNT undefined; the value of endread is always $EOR $. An advance + following endread acts like a startread. If CURCHAR already has value $EOR $ + and endread is performed, CURCHAR will remain the same and endread will, + as usual, have value $EOR $. Diagnostic Function diff --git a/doc/values.md b/doc/values.md index 19c41d6..0639a01 100644 --- a/doc/values.md +++ b/doc/values.md @@ -1,20 +1,23 @@ # Understanding values and properties -I had had the naive assumption that entries on the object list had their CAR pointing to the symbol and their CDR pointing to the related value. Consequently, I could not work out where the property list went. More careful reading of the -text implies, but does not explicitly state, that my naive assumption is wrong. +I had had the naive assumption that entries on the object list had their CAR pointing to the symbol and their CDR pointing to the related value. Consequently, I could not work out where the property list went. More careful reading of [the text] implies, but does not explicitly state, that my naive assumption is wrong. Instead, it appears that the `CAR` points to the symbol, as expected, but the `CAR` points to the property list; and that on the property list there are privileged properties at least as follows: APVAL -: the simple straightforward ordinary value of the symbol, considered a variable; +: the simple straightforward ordinary value of the symbol, considered as a variable; + EXPR : the definition of the function considered as a normal lambda expression (arguments to be evaluated before applying); + FEXPR : the definition of a function which should be applied to unevaluated arguments; + SUBR : the definition of a complied subroutine which should be applied to evaluated arguments; + FSUBR -: the definition of a complied subroutine which should be applied to unevaluated arguments; +: the definition of a complied subroutine which should be applied to unevaluated arguments. I think there was also another privileged property value which contained the property considered as a constant, but I haven't yet confirmed that. @@ -30,6 +33,8 @@ Essentially the properties are tried in turn, and only the first value found is This means that, while the other potential values can be retrieved from the property list, interpreted definitions (if present) will always be preferred to uninterpreted definitions, and lambda function definitions (which evaluate their arguments), where present, will always be preferred to non-lamda definitions, which don't. -**BUT NOTE THAT** the `APVAL` value is saught only when seeking a variable value for the symbol, and the others only when seeking a function value, so Lisp 1.5 is a 'Lisp 2', not a 'Lisp 1'. +**BUT NOTE THAT** the `APVAL` value is sought only when seeking a variable value for the symbol, and the others only when seeking a function value, so Lisp 1.5 is a 'Lisp 2', not a 'Lisp 1'. + + Versions of Beowulf up to and including 0.2.1 used the naive understanding of the architecture; version 0.3.0 *should* use the corrected version. diff --git a/docs/codox/beowulf.bootstrap.html b/docs/codox/beowulf.bootstrap.html index 77f8deb..ed6eb8a 100644 --- a/docs/codox/beowulf.bootstrap.html +++ b/docs/codox/beowulf.bootstrap.html @@ -1,13 +1,13 @@ -beowulf.bootstrap documentation

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beowulf.bootstrap

Lisp as defined in Chapter 1 (pages 1-14) of the Lisp 1.5 Programmer's Manual; that is to say, a very simple Lisp language, which should, I believe, be sufficient in conjunction with the functions provided by beowulf.host, be sufficient to bootstrap the full Lisp 1.5 interpreter..

+beowulf.bootstrap documentation

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beowulf.bootstrap

Lisp as defined in Chapter 1 (pages 1-14) of the Lisp 1.5 Programmer's Manual; that is to say, a very simple Lisp language, which should, I believe, be sufficient in conjunction with the functions provided by beowulf.host, be sufficient to bootstrap the full Lisp 1.5 interpreter..

The convention is adopted that functions in this file with names in ALLUPPERCASE are Lisp 1.5 functions (although written in Clojure) and that therefore all arguments must be numbers, symbols or beowulf.cons_cell.ConsCell objects.

APPLY

(APPLY function args environment depth)

Apply this function to these arguments in this environment and return the result.

-

For bootstrapping, at least, a version of APPLY written in Clojure. All args are assumed to be symbols or beowulf.cons-cell/ConsCell objects. See page 13 of the Lisp 1.5 Programmers Manual.

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CAAAAR

macro

(CAAAAR x)

TODO: write docs

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CAAADR

macro

(CAAADR x)

TODO: write docs

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CAAAR

macro

(CAAAR x)

TODO: write docs

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CAADAR

macro

(CAADAR x)

TODO: write docs

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CAADDR

macro

(CAADDR x)

TODO: write docs

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CAADR

macro

(CAADR x)

TODO: write docs

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CAAR

macro

(CAAR x)

TODO: write docs

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CADAAR

macro

(CADAAR x)

TODO: write docs

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CADADR

macro

(CADADR x)

TODO: write docs

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CADAR

macro

(CADAR x)

TODO: write docs

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CADDAR

macro

(CADDAR x)

TODO: write docs

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CADDDR

macro

(CADDDR x)

TODO: write docs

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CADDR

macro

(CADDR x)

TODO: write docs

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CADR

macro

(CADR x)

TODO: write docs

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CDAAAR

macro

(CDAAAR x)

TODO: write docs

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CDAADR

macro

(CDAADR x)

TODO: write docs

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CDAAR

macro

(CDAAR x)

TODO: write docs

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CDADAR

macro

(CDADAR x)

TODO: write docs

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CDADDR

macro

(CDADDR x)

TODO: write docs

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CDADR

macro

(CDADR x)

TODO: write docs

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CDAR

macro

(CDAR x)

TODO: write docs

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CDDAAR

macro

(CDDAAR x)

TODO: write docs

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CDDADR

macro

(CDDADR x)

TODO: write docs

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CDDAR

macro

(CDDAR x)

TODO: write docs

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CDDDAR

macro

(CDDDAR x)

TODO: write docs

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CDDDDR

macro

(CDDDDR x)

TODO: write docs

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CDDDR

macro

(CDDDR x)

TODO: write docs

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CDDR

macro

(CDDR x)

TODO: write docs

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EVAL

(EVAL expr)(EVAL expr env depth)

Evaluate this expr and return the result. If environment is not passed, it defaults to the current value of the global object list. The depth argument is part of the tracing system and should not be set by user code.

-

All args are assumed to be numbers, symbols or beowulf.cons-cell/ConsCell objects.

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INTEROP

(INTEROP fn-symbol args)

Clojure (or other host environment) interoperation API. fn-symbol is expected to be either

+

For bootstrapping, at least, a version of APPLY written in Clojure. All args are assumed to be symbols or beowulf.cons-cell/ConsCell objects. See page 13 of the Lisp 1.5 Programmers Manual.

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CAAAAR

macro

(CAAAAR x)

TODO: write docs

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CAAADR

macro

(CAAADR x)

TODO: write docs

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CAAAR

macro

(CAAAR x)

TODO: write docs

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CAADAR

macro

(CAADAR x)

TODO: write docs

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CAADDR

macro

(CAADDR x)

TODO: write docs

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CAADR

macro

(CAADR x)

TODO: write docs

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CAAR

macro

(CAAR x)

TODO: write docs

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CADAAR

macro

(CADAAR x)

TODO: write docs

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CADADR

macro

(CADADR x)

TODO: write docs

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CADAR

macro

(CADAR x)

TODO: write docs

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CADDAR

macro

(CADDAR x)

TODO: write docs

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CADDDR

macro

(CADDDR x)

TODO: write docs

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CADDR

macro

(CADDR x)

TODO: write docs

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CADR

macro

(CADR x)

TODO: write docs

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CDAAAR

macro

(CDAAAR x)

TODO: write docs

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CDAADR

macro

(CDAADR x)

TODO: write docs

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CDAAR

macro

(CDAAR x)

TODO: write docs

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CDADAR

macro

(CDADAR x)

TODO: write docs

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CDADDR

macro

(CDADDR x)

TODO: write docs

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CDADR

macro

(CDADR x)

TODO: write docs

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CDAR

macro

(CDAR x)

TODO: write docs

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CDDAAR

macro

(CDDAAR x)

TODO: write docs

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CDDADR

macro

(CDDADR x)

TODO: write docs

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CDDAR

macro

(CDDAR x)

TODO: write docs

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CDDDAR

macro

(CDDDAR x)

TODO: write docs

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CDDDDR

macro

(CDDDDR x)

TODO: write docs

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CDDDR

macro

(CDDDR x)

TODO: write docs

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CDDR

macro

(CDDR x)

TODO: write docs

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EVAL

(EVAL expr)(EVAL expr env depth)

Evaluate this expr and return the result. If environment is not passed, it defaults to the current value of the global object list. The depth argument is part of the tracing system and should not be set by user code.

+

All args are assumed to be numbers, symbols or beowulf.cons-cell/ConsCell objects.

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INTEROP

(INTEROP fn-symbol args)

Clojure (or other host environment) interoperation API. fn-symbol is expected to be either

  1. a symbol bound in the host environment to a function; or
  2. a sequence (list) of symbols forming a qualified path name bound to a function.

Lower case characters cannot normally be represented in Lisp 1.5, so both the upper case and lower case variants of fn-symbol will be tried. If the function you’re looking for has a mixed case name, that is not currently accessible.

args is expected to be a Lisp 1.5 list of arguments to be passed to that function. Return value must be something acceptable to Lisp 1.5, so either a symbol, a number, or a Lisp 1.5 list.

-

If fn-symbol is not found (even when cast to lower case), or is not a function, or the value returned cannot be represented in Lisp 1.5, an exception is thrown with :cause bound to :interop and :detail set to a value representing the actual problem.

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interop-interpret-q-name

(interop-interpret-q-name l)

For interoperation with Clojure, it will often be necessary to pass qualified names that are not representable in Lisp 1.5. This function takes a sequence in the form (PART PART PART... NAME) and returns a symbol in the form PART.PART.PART/NAME. This symbol will then be tried in both that form and lower-cased. Names with hyphens or underscores cannot be represented with this scheme.

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QUOTE

macro

(QUOTE f)

Quote, but in upper case for LISP 1.5

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to-beowulf

(to-beowulf o)

Return a beowulf-native representation of the Clojure object o. Numbers and symbols are unaffected. Collections have to be converted; strings must be converted to symbols.

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to-clojure

(to-clojure l)

If l is a beowulf.cons_cell.ConsCell, return a Clojure list having the same members in the same order.

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uaf

(uaf l path)

Universal access function; l is expected to be an arbitrary LISP list, path a (clojure) list of the characters a and d. Intended to make declaring all those fiddly #'c[ad]+r' functions a bit easier

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\ No newline at end of file +

If fn-symbol is not found (even when cast to lower case), or is not a function, or the value returned cannot be represented in Lisp 1.5, an exception is thrown with :cause bound to :interop and :detail set to a value representing the actual problem.

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interop-interpret-q-name

(interop-interpret-q-name l)

For interoperation with Clojure, it will often be necessary to pass qualified names that are not representable in Lisp 1.5. This function takes a sequence in the form (PART PART PART... NAME) and returns a symbol in the form PART.PART.PART/NAME. This symbol will then be tried in both that form and lower-cased. Names with hyphens or underscores cannot be represented with this scheme.

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QUOTE

macro

(QUOTE f)

Quote, but in upper case for LISP 1.5

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to-beowulf

(to-beowulf o)

Return a beowulf-native representation of the Clojure object o. Numbers and symbols are unaffected. Collections have to be converted; strings must be converted to symbols.

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to-clojure

(to-clojure l)

If l is a beowulf.cons_cell.ConsCell, return a Clojure list having the same members in the same order.

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uaf

(uaf l path)

Universal access function; l is expected to be an arbitrary LISP list, path a (clojure) list of the characters a and d. Intended to make declaring all those fiddly #'c[ad]+r' functions a bit easier

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\ No newline at end of file diff --git a/docs/codox/beowulf.cons-cell.html b/docs/codox/beowulf.cons-cell.html index 1458ba0..e7a05b4 100644 --- a/docs/codox/beowulf.cons-cell.html +++ b/docs/codox/beowulf.cons-cell.html @@ -1,3 +1,3 @@ -beowulf.cons-cell documentation

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beowulf.cons-cell

The fundamental cons cell on which all Lisp structures are built. Lisp 1.5 lists do not necessarily have a sequence as their CDR, and must have both CAR and CDR mutable, so cannot be implemented on top of Clojure lists.

cons-cell?

(cons-cell? o)

Is this object o a beowulf cons-cell?

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F

The canonical false value - different from NIL, which is not canonically false in Lisp 1.5.

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make-beowulf-list

(make-beowulf-list x)

Construct a linked list of cons cells with the same content as the sequence x.

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make-cons-cell

(make-cons-cell car cdr)

Construct a new instance of cons cell with this car and cdr.

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MutableSequence

protocol

Like a sequence, but mutable.

members

getCar

(getCar this)

Return the first element of this sequence.

getCdr

(getCdr this)

like more, q.v., but returns List NIL not Clojure nil when empty.

getUid

(getUid this)

Returns a unique identifier for this object

rplaca

(rplaca this value)

replace the first element of this sequence with this value

rplacd

(rplacd this value)

replace the rest (but-first; cdr) of this sequence with this value

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pretty-print

(pretty-print cell)(pretty-print cell width level)

This isn’t the world’s best pretty printer but it sort of works.

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T

The canonical true value.

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\ No newline at end of file +beowulf.cons-cell documentation

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beowulf.cons-cell

The fundamental cons cell on which all Lisp structures are built. Lisp 1.5 lists do not necessarily have a sequence as their CDR, and must have both CAR and CDR mutable, so cannot be implemented on top of Clojure lists.

cons-cell?

(cons-cell? o)

Is this object o a beowulf cons-cell?

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F

The canonical false value - different from NIL, which is not canonically false in Lisp 1.5.

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make-beowulf-list

(make-beowulf-list x)

Construct a linked list of cons cells with the same content as the sequence x.

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make-cons-cell

(make-cons-cell car cdr)

Construct a new instance of cons cell with this car and cdr.

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MutableSequence

protocol

Like a sequence, but mutable.

members

getCar

(getCar this)

Return the first element of this sequence.

getCdr

(getCdr this)

like more, q.v., but returns List NIL not Clojure nil when empty.

getUid

(getUid this)

Returns a unique identifier for this object

rplaca

(rplaca this value)

replace the first element of this sequence with this value

rplacd

(rplacd this value)

replace the rest (but-first; cdr) of this sequence with this value

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pretty-print

(pretty-print cell)(pretty-print cell width level)

This isn’t the world’s best pretty printer but it sort of works.

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T

The canonical true value.

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\ No newline at end of file diff --git a/docs/codox/beowulf.core.html b/docs/codox/beowulf.core.html index a2400c6..b4494b3 100644 --- a/docs/codox/beowulf.core.html +++ b/docs/codox/beowulf.core.html @@ -1,3 +1,3 @@ -beowulf.core documentation

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beowulf.core

Essentially, the -main function and the bootstrap read-eval-print loop.

-main

(-main & opts)

Parse options, print the banner, read the init file if any, and enter the read/eval/print loop.

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cli-options

TODO: write docs

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repl

(repl prompt)

Read/eval/print loop.

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stop-word

TODO: write docs

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\ No newline at end of file +beowulf.core documentation

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beowulf.core

Essentially, the -main function and the bootstrap read-eval-print loop.

-main

(-main & opts)

Parse options, print the banner, read the init file if any, and enter the read/eval/print loop.

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cli-options

TODO: write docs

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repl

(repl prompt)

Read/eval/print loop.

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stop-word

TODO: write docs

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\ No newline at end of file diff --git a/docs/codox/beowulf.gendoc.html b/docs/codox/beowulf.gendoc.html index b0ab126..331c022 100644 --- a/docs/codox/beowulf.gendoc.html +++ b/docs/codox/beowulf.gendoc.html @@ -1,4 +1,4 @@ -beowulf.gendoc documentation

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beowulf.gendoc

Generate table of documentation of Lisp symbols and functions.

-

NOTE: this is very hacky. You almost certainly do not want to use this!

find-documentation

(find-documentation entry)

Find appropriate documentation for this entry from the oblist.

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gen-doc-table

(gen-doc-table)(gen-doc-table sysfile)

TODO: write docs

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gen-index

(gen-index)(gen-index url destination)

TODO: write docs

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host-functions

Functions which we can infer are written in Clojure.

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infer-implementation

(infer-implementation entry)

TODO: write docs

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infer-signature

(infer-signature entry)

Infer the signature of the function value of this oblist entry, if any.

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infer-type

(infer-type entry)

Try to work out what this entry from the oblist actually represents.

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\ No newline at end of file +beowulf.gendoc documentation

Project

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beowulf.gendoc

Generate table of documentation of Lisp symbols and functions.

+

NOTE: this is very hacky. You almost certainly do not want to use this!

find-documentation

(find-documentation entry)

Find appropriate documentation for this entry from the oblist.

view source

gen-doc-table

(gen-doc-table)

TODO: write docs

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gen-index

(gen-index)(gen-index url destination)

TODO: write docs

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host-functions

Functions which we can infer are written in Clojure. We need to collect these at run-time, not compile time, hence memoised function, not variable.

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infer-implementation

(infer-implementation entry)

TODO: write docs

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infer-signature

(infer-signature entry)

Infer the signature of the function value of this oblist entry, if any.

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infer-type

(infer-type entry)

Try to work out what this entry from the oblist actually represents.

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open-doc

(open-doc symbol)

Open the documentation page for this symbol, if known, in the default web browser.

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\ No newline at end of file diff --git a/docs/codox/beowulf.host.html b/docs/codox/beowulf.host.html index a2a6253..146e37c 100644 --- a/docs/codox/beowulf.host.html +++ b/docs/codox/beowulf.host.html @@ -1,12 +1,14 @@ -beowulf.host documentation

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beowulf.host

provides Lisp 1.5 functions which can’t be (or can’t efficiently be) implemented in Lisp 1.5, which therefore need to be implemented in the host language, in this case Clojure.

ADD1

(ADD1 x)

TODO: write docs

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AND

(AND & args)

T if and only if none of my args evaluate to either F or NIL, else F.

-

In beowulf.host principally because I don’t yet feel confident to define varargs functions in Lisp.

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ASSOC

(ASSOC x a)

If a is an association list such as the one formed by PAIRLIS in the above example, then assoc will produce the first pair whose first term is x. Thus it is a table searching function.

-

All args are assumed to be beowulf.cons-cell/ConsCell objects. See page 12 of the Lisp 1.5 Programmers Manual.

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ATOM

(ATOM x)

Returns T if and only if the argument x is bound to an atom; else F. It is not clear to me from the documentation whether (ATOM 7) should return T or F. I’m going to assume T.

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ATOM?

macro

(ATOM? x)

The convention of returning F from predicates, rather than NIL, is going to tie me in knots. This is a variant of ATOM which returns NIL on failure.

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CAAAAR

macro

(CAAAAR x)

TODO: write docs

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CAAADR

macro

(CAAADR x)

TODO: write docs

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CAAAR

macro

(CAAAR x)

TODO: write docs

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CAADAR

macro

(CAADAR x)

TODO: write docs

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CAADDR

macro

(CAADDR x)

TODO: write docs

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CAADR

macro

(CAADR x)

TODO: write docs

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CAAR

macro

(CAAR x)

TODO: write docs

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CADAAR

macro

(CADAAR x)

TODO: write docs

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CADADR

macro

(CADADR x)

TODO: write docs

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CADAR

macro

(CADAR x)

TODO: write docs

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CADDAR

macro

(CADDAR x)

TODO: write docs

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CADDDR

macro

(CADDDR x)

TODO: write docs

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CADDR

macro

(CADDR x)

TODO: write docs

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CADR

macro

(CADR x)

TODO: write docs

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CAR

(CAR x)

Return the item indicated by the first pointer of a pair. NIL is treated specially: the CAR of NIL is NIL.

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CDAAAR

macro

(CDAAAR x)

TODO: write docs

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CDAADR

macro

(CDAADR x)

TODO: write docs

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CDAAR

macro

(CDAAR x)

TODO: write docs

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CDADAR

macro

(CDADAR x)

TODO: write docs

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CDADDR

macro

(CDADDR x)

TODO: write docs

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CDADR

macro

(CDADR x)

TODO: write docs

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CDAR

macro

(CDAR x)

TODO: write docs

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CDDAAR

macro

(CDDAAR x)

TODO: write docs

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CDDADR

macro

(CDDADR x)

TODO: write docs

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CDDAR

macro

(CDDAR x)

TODO: write docs

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CDDDAR

macro

(CDDDAR x)

TODO: write docs

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CDDDDR

macro

(CDDDDR x)

TODO: write docs

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CDDDR

macro

(CDDDR x)

TODO: write docs

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CDDR

macro

(CDDR x)

TODO: write docs

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CDR

(CDR x)

Return the item indicated by the second pointer of a pair. NIL is treated specially: the CDR of NIL is NIL.

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CONS

(CONS car cdr)

Construct a new instance of cons cell with this car and cdr.

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DEFINE

(DEFINE args)

Bootstrap-only version of DEFINE which, post boostrap, can be overwritten in LISP.

-

The single argument to DEFINE should be an assoc list which should be nconc’ed onto the front of the oblist. Broadly, (SETQ OBLIST (NCONC ARG1 OBLIST))

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DIFFERENCE

(DIFFERENCE x y)

TODO: write docs

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EQ

(EQ x y)

Returns T if and only if both x and y are bound to the same atom, else NIL.

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EQUAL

(EQUAL x y)

This is a predicate that is true if its two arguments are identical S-expressions, and false if they are different. (The elementary predicate EQ is defined only for atomic arguments.) The definition of EQUAL is an example of a conditional expression inside a conditional expression.

-

NOTE: returns F on failure, not NIL

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ERROR

(ERROR & args)

Throw an error

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FIXP

(FIXP x)

TODO: write docs

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GENSYM

(GENSYM)

Generate a unique symbol.

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GREATERP

(GREATERP x y)

TODO: write docs

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lax?

(lax? symbol)

Are we in lax mode? If so. return true; is not, throw an exception with this symbol.

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LESSP

(LESSP x y)

TODO: write docs

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LIST

(LIST & args)

TODO: write docs

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NILP

macro

(NILP x)

Not part of LISP 1.5: T if o is NIL, else NIL.

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NULL

macro

(NULL x)

Returns T if and only if the argument x is bound to NIL; else F.

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NUMBERP

(NUMBERP x)

TODO: write docs

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OBLIST

(OBLIST)

Return a list of the symbols currently bound on the object list.

-

NOTE THAT in the Lisp 1.5 manual, footnote at the bottom of page 69, it implies that an argument can be passed but I’m not sure of the semantics of this.

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PAIRLIS

(PAIRLIS x y a)

This function gives the list of pairs of corresponding elements of the lists x and y, and APPENDs this to the list a. The resultant list of pairs, which is like a table with two columns, is called an association list.

+beowulf.host documentation

Project

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beowulf.host

provides Lisp 1.5 functions which can’t be (or can’t efficiently be) implemented in Lisp 1.5, which therefore need to be implemented in the host language, in this case Clojure.

ADD1

(ADD1 x)

TODO: write docs

view source

AND

(AND & args)

T if and only if none of my args evaluate to either F or NIL, else F.

+

In beowulf.host principally because I don’t yet feel confident to define varargs functions in Lisp.

view source

ASSOC

(ASSOC x a)

If a is an association list such as the one formed by PAIRLIS in the above example, then assoc will produce the first pair whose first term is x. Thus it is a table searching function.

+

All args are assumed to be beowulf.cons-cell/ConsCell objects. See page 12 of the Lisp 1.5 Programmers Manual.

+

NOTE THAT this function is overridden by an implementation in Lisp, but is currently still present for bootstrapping.

view source

ATOM

(ATOM x)

Returns T if and only if the argument x is bound to an atom; else F. It is not clear to me from the documentation whether (ATOM 7) should return T or F. I’m going to assume T.

view source

ATOM?

macro

(ATOM? x)

The convention of returning F from predicates, rather than NIL, is going to tie me in knots. This is a variant of ATOM which returns NIL on failure.

view source

CAAAAR

macro

(CAAAAR x)

TODO: write docs

view source

CAAADR

macro

(CAAADR x)

TODO: write docs

view source

CAAAR

macro

(CAAAR x)

TODO: write docs

view source

CAADAR

macro

(CAADAR x)

TODO: write docs

view source

CAADDR

macro

(CAADDR x)

TODO: write docs

view source

CAADR

macro

(CAADR x)

TODO: write docs

view source

CAAR

macro

(CAAR x)

TODO: write docs

view source

CADAAR

macro

(CADAAR x)

TODO: write docs

view source

CADADR

macro

(CADADR x)

TODO: write docs

view source

CADAR

macro

(CADAR x)

TODO: write docs

view source

CADDAR

macro

(CADDAR x)

TODO: write docs

view source

CADDDR

macro

(CADDDR x)

TODO: write docs

view source

CADDR

macro

(CADDR x)

TODO: write docs

view source

CADR

macro

(CADR x)

TODO: write docs

view source

CAR

(CAR x)

Return the item indicated by the first pointer of a pair. NIL is treated specially: the CAR of NIL is NIL.

view source

CDAAAR

macro

(CDAAAR x)

TODO: write docs

view source

CDAADR

macro

(CDAADR x)

TODO: write docs

view source

CDAAR

macro

(CDAAR x)

TODO: write docs

view source

CDADAR

macro

(CDADAR x)

TODO: write docs

view source

CDADDR

macro

(CDADDR x)

TODO: write docs

view source

CDADR

macro

(CDADR x)

TODO: write docs

view source

CDAR

macro

(CDAR x)

TODO: write docs

view source

CDDAAR

macro

(CDDAAR x)

TODO: write docs

view source

CDDADR

macro

(CDDADR x)

TODO: write docs

view source

CDDAR

macro

(CDDAR x)

TODO: write docs

view source

CDDDAR

macro

(CDDDAR x)

TODO: write docs

view source

CDDDDR

macro

(CDDDDR x)

TODO: write docs

view source

CDDDR

macro

(CDDDR x)

TODO: write docs

view source

CDDR

macro

(CDDR x)

TODO: write docs

view source

CDR

(CDR x)

Return the item indicated by the second pointer of a pair. NIL is treated specially: the CDR of NIL is NIL.

view source

CONS

(CONS car cdr)

Construct a new instance of cons cell with this car and cdr.

view source

CONSP

(CONSP o)

Return T if object o is a cons cell, else F.

+

NOTE THAT this is an extension function, not available in strct mode. I believe that Lisp 1.5 did not have any mechanism for testing whether an argument was, or was not, a cons cell.

view source

DEFINE

(DEFINE args)

Bootstrap-only version of DEFINE which, post boostrap, can be overwritten in LISP.

+

The single argument to DEFINE should be an assoc list which should be nconc’ed onto the front of the oblist. Broadly, (SETQ OBLIST (NCONC ARG1 OBLIST))

view source

DIFFERENCE

(DIFFERENCE x y)

TODO: write docs

view source

DOC

(DOC symbol)

Open the page for this symbol in the Lisp 1.5 manual, if known, in the default web browser.

+

NOTE THAT this is an extension function, not available in strct mode.

view source

EQ

(EQ x y)

Returns T if and only if both x and y are bound to the same atom, else NIL.

view source

EQUAL

(EQUAL x y)

This is a predicate that is true if its two arguments are identical S-expressions, and false if they are different. (The elementary predicate EQ is defined only for atomic arguments.) The definition of EQUAL is an example of a conditional expression inside a conditional expression.

+

NOTE: returns F on failure, not NIL

view source

ERROR

(ERROR & args)

Throw an error

view source

FIXP

(FIXP x)

TODO: write docs

view source

GENSYM

(GENSYM)

Generate a unique symbol.

view source

GREATERP

(GREATERP x y)

TODO: write docs

view source

lax?

(lax? symbol)

Are we in lax mode? If so. return true; is not, throw an exception with this symbol.

view source

LESSP

(LESSP x y)

TODO: write docs

view source

LIST

(LIST & args)

TODO: write docs

view source

NILP

macro

(NILP x)

Not part of LISP 1.5: T if o is NIL, else NIL.

view source

NULL

macro

(NULL x)

Returns T if and only if the argument x is bound to NIL; else F.

view source

NUMBERP

(NUMBERP x)

TODO: write docs

view source

OBLIST

(OBLIST)

Return a list of the symbols currently bound on the object list.

+

NOTE THAT in the Lisp 1.5 manual, footnote at the bottom of page 69, it implies that an argument can be passed but I’m not sure of the semantics of this.

view source

PAIRLIS

(PAIRLIS x y a)

This function gives the list of pairs of corresponding elements of the lists x and y, and APPENDs this to the list a. The resultant list of pairs, which is like a table with two columns, is called an association list.

Eessentially, it builds the environment on the stack, implementing shallow binding.

-

All args are assumed to be beowulf.cons-cell/ConsCell objects. See page 12 of the Lisp 1.5 Programmers Manual.

view source

PLUS

(PLUS & args)

TODO: write docs

view source

QUOTIENT

(QUOTIENT x y)

I’m not certain from the documentation whether Lisp 1.5 QUOTIENT returned the integer part of the quotient, or a realnum representing the whole quotient. I am for now implementing the latter.

view source

REMAINDER

(REMAINDER x y)

TODO: write docs

view source

RPLACA

(RPLACA cell value)

Replace the CAR pointer of this cell with this value. Dangerous, should really not exist, but does in Lisp 1.5 (and was important for some performance hacks in early Lisps)

view source

RPLACD

(RPLACD cell value)

Replace the CDR pointer of this cell with this value. Dangerous, should really not exist, but does in Lisp 1.5 (and was important for some performance hacks in early Lisps)

view source

SET

(SET symbol val)

Implementation of SET in Clojure. Add to the oblist a binding of the value of var to the value of val. NOTE WELL: this is not SETQ!

view source

SUB1

(SUB1 x)

TODO: write docs

view source

SUBLIS

(SUBLIS a y)

Here a is assumed to be an association list of the form ((ul . vl)...(un . vn)), where the us are atomic, and y is any S-expression. What SUBLIS does, is to treat the us as variables when they occur in y, and to SUBSTitute the corresponding vs from the pair list.

-

My interpretation is that this is variable binding in the stack frame.

-

All args are assumed to be beowulf.cons-cell/ConsCell objects. See page 12 of the Lisp 1.5 Programmers Manual.

view source

SUBST

(SUBST x y z)

This function gives the result of substituting the S-expression x for all occurrences of the atomic symbol y in the S-expression z.

view source

TIMES

(TIMES & args)

TODO: write docs

view source

TRACE

(TRACE s)

Add this symbol s to the set of symbols currently being traced. If s is not a symbol, does nothing.

view source

traced-symbols

Symbols currently being traced.

view source

traced?

(traced? s)

Return true iff s is a symbol currently being traced, else nil.

view source

uaf

(uaf l path)

Universal access function; l is expected to be an arbitrary LISP list, path a (clojure) list of the characters a and d. Intended to make declaring all those fiddly #'c[ad]+r' functions a bit easier

view source

UNTRACE

(UNTRACE s)

TODO: write docs

view source
\ No newline at end of file +

All args are assumed to be beowulf.cons-cell/ConsCell objects. See page 12 of the Lisp 1.5 Programmers Manual.

+

NOTE THAT this function is overridden by an implementation in Lisp, but is currently still present for bootstrapping.

view source

PLUS

(PLUS & args)

TODO: write docs

view source

QUOTIENT

(QUOTIENT x y)

I’m not certain from the documentation whether Lisp 1.5 QUOTIENT returned the integer part of the quotient, or a realnum representing the whole quotient. I am for now implementing the latter.

view source

REMAINDER

(REMAINDER x y)

TODO: write docs

view source

RPLACA

(RPLACA cell value)

Replace the CAR pointer of this cell with this value. Dangerous, should really not exist, but does in Lisp 1.5 (and was important for some performance hacks in early Lisps)

view source

RPLACD

(RPLACD cell value)

Replace the CDR pointer of this cell with this value. Dangerous, should really not exist, but does in Lisp 1.5 (and was important for some performance hacks in early Lisps)

view source

SET

(SET symbol val)

Implementation of SET in Clojure. Add to the oblist a binding of the value of var to the value of val. NOTE WELL: this is not SETQ!

view source

SUB1

(SUB1 x)

TODO: write docs

view source

TIMES

(TIMES & args)

TODO: write docs

view source

TRACE

(TRACE s)

Add this symbol s to the set of symbols currently being traced. If s is not a symbol, does nothing.

view source

traced-symbols

Symbols currently being traced.

view source

traced?

(traced? s)

Return true iff s is a symbol currently being traced, else nil.

view source

uaf

(uaf l path)

Universal access function; l is expected to be an arbitrary LISP list, path a (clojure) list of the characters a and d. Intended to make declaring all those fiddly #'c[ad]+r' functions a bit easier

view source

UNTRACE

(UNTRACE s)

TODO: write docs

view source
\ No newline at end of file diff --git a/docs/codox/beowulf.io.html b/docs/codox/beowulf.io.html index 432dd61..1158db6 100644 --- a/docs/codox/beowulf.io.html +++ b/docs/codox/beowulf.io.html @@ -1,6 +1,6 @@ -beowulf.io documentation

Project

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Namespaces

Public Vars

beowulf.io

Non-standard extensions to Lisp 1.5 to read and write to the filesystem.

+beowulf.io documentation

Project

Topics

Namespaces

Public Vars

beowulf.io

Non-standard extensions to Lisp 1.5 to read and write to the filesystem.

Lisp 1.5 had only READ, which read one S-Expression at a time, and various forms of PRIN* functions, which printed to the line printer. There was also PUNCH, which wrote to a card punch. It does not seem that there was any concept of an interactive terminal.

See Appendix E, OVERLORD - THE MONITOR, and Appendix F, LISP INPUT AND OUTPUT.

@@ -8,4 +8,6 @@ AND OUTPUT.

Hence functions SYSOUT and SYSIN, which do just that.

default-sysout

TODO: write docs

view source

SYSIN

(SYSIN)(SYSIN filename)

Read the contents of the file at this filename into the object list.

If the file is not a valid Beowulf sysout file, this will probably corrupt the system, you have been warned. File paths will be considered relative to the filepath set when starting Lisp.

It is intended that sysout files can be read both from resources within the jar file, and from the file system. If a named file exists in both the file system and the resources, the file system will be preferred.

-

NOTE THAT if the provided filename does not end with .lsp (which, if you’re writing it from the Lisp REPL, it won’t), the extension .lsp will be appended.

view source

SYSOUT

(SYSOUT)(SYSOUT filepath)

Dump the current content of the object list to file. If no filepath is specified, a file name will be constructed of the symbol Sysout and the current date. File paths will be considered relative to the filepath set when starting Lisp.

view source
\ No newline at end of file +

NOTE THAT if the provided filename does not end with .lsp (which, if you’re writing it from the Lisp REPL, it won’t), the extension .lsp will be appended.

+

NOTE THAT this is an extension function, not available in strct mode.

view source

SYSOUT

(SYSOUT)(SYSOUT filepath)

Dump the current content of the object list to file. If no filepath is specified, a file name will be constructed of the symbol Sysout and the current date. File paths will be considered relative to the filepath set when starting Lisp.

+

NOTE THAT this is an extension function, not available in strct mode.

view source
\ No newline at end of file diff --git a/docs/codox/beowulf.manual.html b/docs/codox/beowulf.manual.html index f31ee80..fab729e 100644 --- a/docs/codox/beowulf.manual.html +++ b/docs/codox/beowulf.manual.html @@ -1,3 +1,3 @@ -beowulf.manual documentation

Project

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Public Vars

beowulf.manual

Experimental code for accessing the manual online.

*manual-url*

dynamic

TODO: write docs

view source

format-page-references

(format-page-references fn-symbol)

Format page references from the manual index for the function whose name is fn-symbol.

view source

index

This is data extracted from the index pages of Lisp 1.5 Programmer's Manual. It’s here in the hope that we can automatically link to an online PDF link to the manual when the user invokes a function probably called DOC or HELP.

view source

page-url

(page-url page-no)

Format the URL for the page in the manual with this page-no.

view source
\ No newline at end of file +beowulf.manual documentation

Project

Topics

Namespaces

Public Vars

beowulf.manual

Experimental code for accessing the manual online.

*manual-url*

dynamic

TODO: write docs

view source

format-page-references

(format-page-references fn-symbol)

Format page references from the manual index for the function whose name is fn-symbol.

view source

index

This is data extracted from the index pages of Lisp 1.5 Programmer's Manual. It’s here in the hope that we can automatically link to an online PDF link to the manual when the user invokes a function probably called DOC or HELP.

view source

page-url

(page-url page-no)

Format the URL for the page in the manual with this page-no.

view source
\ No newline at end of file diff --git a/docs/codox/beowulf.oblist.html b/docs/codox/beowulf.oblist.html index d11a024..a71aac0 100644 --- a/docs/codox/beowulf.oblist.html +++ b/docs/codox/beowulf.oblist.html @@ -1,5 +1,5 @@ -beowulf.oblist documentation

Project

Topics

Namespaces

Public Vars

beowulf.oblist

A namespace mainly devoted to the object list and other top level global variables.

+beowulf.oblist documentation

Project

Topics

Namespaces

Public Vars

beowulf.oblist

A namespace mainly devoted to the object list and other top level global variables.

Yes, this makes little sense, but if you put them anywhere else you end up in cyclic dependency hell.

*options*

dynamic

Command line options from invocation.

view source

NIL

The canonical empty list symbol.

TODO: this doesn’t really work, because (from Clojure) (empty? NIL) throws an exception. It might be better to subclass beowulf.cons_cell.ConsCell to create a new singleton class Nil which overrides the empty method of IPersistentCollection?

view source

oblist

The default environment.

view source
\ No newline at end of file diff --git a/docs/codox/beowulf.read.html b/docs/codox/beowulf.read.html index 6d41e58..b985082 100644 --- a/docs/codox/beowulf.read.html +++ b/docs/codox/beowulf.read.html @@ -1,6 +1,6 @@ -beowulf.read documentation

Project

Topics

Namespaces

Public Vars

beowulf.read

This provides the reader required for boostrapping. It’s not a bad reader - it provides feedback on errors found in the input - but it isn’t the real Lisp reader.

+beowulf.read documentation

Project

Topics

Namespaces

Public Vars

beowulf.read

This provides the reader required for boostrapping. It’s not a bad reader - it provides feedback on errors found in the input - but it isn’t the real Lisp reader.

Intended deviations from the behaviour of the real Lisp reader are as follows:

  1. It reads the meta-expression language MEXPR in addition to the symbolic expression language SEXPR, which I do not believe the Lisp 1.5 reader ever did;
    2. diff --git a/docs/codox/beowulf.reader.char-reader.html b/docs/codox/beowulf.reader.char-reader.html index 3f81a15..d607448 100644 --- a/docs/codox/beowulf.reader.char-reader.html +++ b/docs/codox/beowulf.reader.char-reader.html @@ -1,6 +1,6 @@ -beowulf.reader.char-reader documentation

    Project

    Topics

    Namespaces

    Public Vars

    beowulf.reader.char-reader

    Provide sensible line editing, auto completion, and history recall.

    +beowulf.reader.char-reader documentation

    Project

    Topics

    Namespaces

    Public Vars

    beowulf.reader.char-reader

    Provide sensible line editing, auto completion, and history recall.

    None of what’s needed here is really working yet, and a pull request with a working implementation would be greatly welcomed.

    What’s needed (rough specification)

      diff --git a/docs/codox/beowulf.reader.generate.html b/docs/codox/beowulf.reader.generate.html index 8b6f86b..65627db 100644 --- a/docs/codox/beowulf.reader.generate.html +++ b/docs/codox/beowulf.reader.generate.html @@ -1,6 +1,6 @@ -beowulf.reader.generate documentation

      Project

      Topics

      Namespaces

      Public Vars

      beowulf.reader.generate

      Generating S-Expressions from parse trees.

      +beowulf.reader.generate documentation

      Project

      Topics

      Namespaces

      Public Vars

      beowulf.reader.generate

      Generating S-Expressions from parse trees.

      From Lisp 1.5 Programmers Manual, page 10

      Note that I’ve retyped much of this, since copy/pasting out of PDF is less than reliable. Any typos are mine.

      Quote starts:

      diff --git a/docs/codox/beowulf.reader.macros.html b/docs/codox/beowulf.reader.macros.html index e4dd087..af18089 100644 --- a/docs/codox/beowulf.reader.macros.html +++ b/docs/codox/beowulf.reader.macros.html @@ -1,5 +1,5 @@ -beowulf.reader.macros documentation

      Project

      Topics

      Namespaces

      Public Vars

      beowulf.reader.macros

      Can I implement reader macros? let’s see!

      +beowulf.reader.macros documentation

      Project

      Topics

      Namespaces

      Public Vars

      beowulf.reader.macros

      Can I implement reader macros? let’s see!

      We don’t need (at least, in the Clojure reader) to rewrite forms like 'FOO, because that’s handled by the parser. But we do need to rewrite things which don’t evaluate their arguments, like SETQ, because (unless LABEL does it, which I’m not yet sure of) we’re not yet able to implement things which don’t evaluate arguments.

      TODO: at this stage, the following should probably also be read macros: DEFINE

      *readmacros*

      dynamic

      TODO: write docs

      view source

      expand-macros

      (expand-macros form)

      TODO: write docs

      view source
      \ No newline at end of file diff --git a/docs/codox/beowulf.reader.parser.html b/docs/codox/beowulf.reader.parser.html index f31c302..b091fc9 100644 --- a/docs/codox/beowulf.reader.parser.html +++ b/docs/codox/beowulf.reader.parser.html @@ -1,3 +1,3 @@ -beowulf.reader.parser documentation

      Project

      Topics

      Namespaces

      Public Vars

      beowulf.reader.parser

      The actual parser, supporting both S-expression and M-expression syntax.

      parse

      Parse a string presented as argument into a parse tree which can then be operated upon further.

      view source
      \ No newline at end of file +beowulf.reader.parser documentation

      Project

      Topics

      Namespaces

      Public Vars

      beowulf.reader.parser

      The actual parser, supporting both S-expression and M-expression syntax.

      parse

      Parse a string presented as argument into a parse tree which can then be operated upon further.

      view source
      \ No newline at end of file diff --git a/docs/codox/beowulf.reader.simplify.html b/docs/codox/beowulf.reader.simplify.html index 25d3f90..55f654a 100644 --- a/docs/codox/beowulf.reader.simplify.html +++ b/docs/codox/beowulf.reader.simplify.html @@ -1,4 +1,4 @@ -beowulf.reader.simplify documentation

      Project

      Topics

      Namespaces

      Public Vars

      beowulf.reader.simplify

      Simplify parse trees. Be aware that this is very tightly coupled with the parser.

      remove-nesting

      (remove-nesting tree context)

      TODO: write docs

      view source

      remove-optional-space

      (remove-optional-space tree)

      TODO: write docs

      view source

      simplify

      (simplify p)

      Simplify this parse tree p. If p is an instaparse failure object, throw an ex-info, with p as the value of its :failure key. Calls remove-optional-space before processing.

      view source

      simplify-tree

      (simplify-tree p)(simplify-tree p context)

      Simplify this parse tree p. If p is an instaparse failure object, throw an ex-info, with p as the value of its :failure key.

      +beowulf.reader.simplify documentation

      Project

      Topics

      Namespaces

      Public Vars

      beowulf.reader.simplify

      Simplify parse trees. Be aware that this is very tightly coupled with the parser.

      remove-nesting

      (remove-nesting tree context)

      TODO: write docs

      view source

      remove-optional-space

      (remove-optional-space tree)

      TODO: write docs

      view source

      simplify

      (simplify p)

      Simplify this parse tree p. If p is an instaparse failure object, throw an ex-info, with p as the value of its :failure key. Calls remove-optional-space before processing.

      view source

      simplify-tree

      (simplify-tree p)(simplify-tree p context)

      Simplify this parse tree p. If p is an instaparse failure object, throw an ex-info, with p as the value of its :failure key.

      NOTE THAT it is assumed that remove-optional-space has been run on the parse tree BEFORE it is passed to simplify-tree.

      view source
      \ No newline at end of file diff --git a/docs/codox/beowulf.scratch.html b/docs/codox/beowulf.scratch.html index f59675e..bdd1149 100644 --- a/docs/codox/beowulf.scratch.html +++ b/docs/codox/beowulf.scratch.html @@ -1,3 +1,3 @@ -beowulf.scratch documentation

      Project

      Topics

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      Public Vars

      beowulf.scratch

      This namespace is for temporary functions and is intentionally excluded from Git.

      accessor-body

      (accessor-body l v)

      TODO: write docs

      view source

      accessor-symbol

      (accessor-symbol l)

      Generate a symbol by prepending C and appending A to this list of string fragments l.

      view source

      accessors-generator

      (accessors-generator n)

      TODO: write docs

      view source

      manual-index

      TODO: write docs

      view source
      \ No newline at end of file +beowulf.scratch documentation

      Project

      Topics

      Namespaces

      Public Vars

      beowulf.scratch

      This namespace is for temporary functions and is intentionally excluded from Git.

      accessor-body

      (accessor-body l v)

      TODO: write docs

      view source

      accessor-symbol

      (accessor-symbol l)

      Generate a symbol by prepending C and appending A to this list of string fragments l.

      view source

      accessors-generator

      (accessors-generator n)

      TODO: write docs

      view source

      manual-index

      TODO: write docs

      view source

      mogrify-plist

      (mogrify-plist entry fns)

      TODO: write docs

      view source
      \ No newline at end of file diff --git a/docs/codox/index.html b/docs/codox/index.html index b4c2e6a..b6001d0 100644 --- a/docs/codox/index.html +++ b/docs/codox/index.html @@ -1,3 +1,3 @@ -Beowulf 0.3.0-SNAPSHOT

      Project

      Topics

      Namespaces

      Beowulf 0.3.0-SNAPSHOT

      Released under the GPL-2.0-or-later

      An implementation of LISP 1.5 in Clojure.

      Installation

      To install, add the following dependency to your project or build file:

      [beowulf "0.3.0-SNAPSHOT"]

      Topics

      Namespaces

      beowulf.bootstrap

      Lisp as defined in Chapter 1 (pages 1-14) of the Lisp 1.5 Programmer's Manual; that is to say, a very simple Lisp language, which should, I believe, be sufficient in conjunction with the functions provided by beowulf.host, be sufficient to bootstrap the full Lisp 1.5 interpreter..

      Public variables and functions:

      beowulf.cons-cell

      The fundamental cons cell on which all Lisp structures are built. Lisp 1.5 lists do not necessarily have a sequence as their CDR, and must have both CAR and CDR mutable, so cannot be implemented on top of Clojure lists.

      Public variables and functions:

      beowulf.core

      Essentially, the -main function and the bootstrap read-eval-print loop.

      Public variables and functions:

      beowulf.gendoc

      Generate table of documentation of Lisp symbols and functions.

      Public variables and functions:

      beowulf.host

      provides Lisp 1.5 functions which can’t be (or can’t efficiently be) implemented in Lisp 1.5, which therefore need to be implemented in the host language, in this case Clojure.

      Public variables and functions:

      beowulf.io

      Non-standard extensions to Lisp 1.5 to read and write to the filesystem.

      Public variables and functions:

      beowulf.manual

      Experimental code for accessing the manual online.

      Public variables and functions:

      beowulf.oblist

      A namespace mainly devoted to the object list and other top level global variables.

      Public variables and functions:

      beowulf.read

      This provides the reader required for boostrapping. It’s not a bad reader - it provides feedback on errors found in the input - but it isn’t the real Lisp reader.

      Public variables and functions:

      beowulf.reader.char-reader

      Provide sensible line editing, auto completion, and history recall.

      Public variables and functions:

      beowulf.reader.generate

      Generating S-Expressions from parse trees.

      Public variables and functions:

      beowulf.reader.macros

      Can I implement reader macros? let’s see!

      Public variables and functions:

      beowulf.reader.parser

      The actual parser, supporting both S-expression and M-expression syntax.

      Public variables and functions:

      beowulf.reader.simplify

      Simplify parse trees. Be aware that this is very tightly coupled with the parser.

      Public variables and functions:

      beowulf.scratch

      This namespace is for temporary functions and is intentionally excluded from Git.

      Public variables and functions:

      \ No newline at end of file +Beowulf 0.3.0-SNAPSHOT

      Project

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      Namespaces

      Beowulf 0.3.0-SNAPSHOT

      Released under the GPL-2.0-or-later

      An implementation of LISP 1.5 in Clojure.

      Installation

      To install, add the following dependency to your project or build file:

      [beowulf "0.3.0-SNAPSHOT"]

      Topics

      Namespaces

      beowulf.bootstrap

      Lisp as defined in Chapter 1 (pages 1-14) of the Lisp 1.5 Programmer's Manual; that is to say, a very simple Lisp language, which should, I believe, be sufficient in conjunction with the functions provided by beowulf.host, be sufficient to bootstrap the full Lisp 1.5 interpreter..

      Public variables and functions:

      beowulf.cons-cell

      The fundamental cons cell on which all Lisp structures are built. Lisp 1.5 lists do not necessarily have a sequence as their CDR, and must have both CAR and CDR mutable, so cannot be implemented on top of Clojure lists.

      Public variables and functions:

      beowulf.core

      Essentially, the -main function and the bootstrap read-eval-print loop.

      Public variables and functions:

      beowulf.gendoc

      Generate table of documentation of Lisp symbols and functions.

      Public variables and functions:

      beowulf.host

      provides Lisp 1.5 functions which can’t be (or can’t efficiently be) implemented in Lisp 1.5, which therefore need to be implemented in the host language, in this case Clojure.

      Public variables and functions:

      beowulf.io

      Non-standard extensions to Lisp 1.5 to read and write to the filesystem.

      Public variables and functions:

      beowulf.manual

      Experimental code for accessing the manual online.

      Public variables and functions:

      beowulf.oblist

      A namespace mainly devoted to the object list and other top level global variables.

      Public variables and functions:

      beowulf.read

      This provides the reader required for boostrapping. It’s not a bad reader - it provides feedback on errors found in the input - but it isn’t the real Lisp reader.

      Public variables and functions:

      beowulf.reader.char-reader

      Provide sensible line editing, auto completion, and history recall.

      Public variables and functions:

      beowulf.reader.generate

      Generating S-Expressions from parse trees.

      Public variables and functions:

      beowulf.reader.macros

      Can I implement reader macros? let’s see!

      Public variables and functions:

      beowulf.reader.parser

      The actual parser, supporting both S-expression and M-expression syntax.

      Public variables and functions:

      beowulf.reader.simplify

      Simplify parse trees. Be aware that this is very tightly coupled with the parser.

      Public variables and functions:

      beowulf.scratch

      This namespace is for temporary functions and is intentionally excluded from Git.

      Public variables and functions:

      \ No newline at end of file diff --git a/docs/codox/intro.html b/docs/codox/intro.html index 654591c..a765e07 100644 --- a/docs/codox/intro.html +++ b/docs/codox/intro.html @@ -1,7 +1,7 @@ -beowulf

      Project

      Topics

      Namespaces

      beowulf

      -

      LISP 1.5 is to all Lisp dialects as Beowulf is to Emglish literature.

      +beowulf

      Project

      Topics

      Namespaces

      beowulf

      +

      LISP 1.5 is to all Lisp dialects as Beowulf is to English literature.

      What this is

      A work-in-progress towards an implementation of Lisp 1.5 in Clojure. The objective is to build a complete and accurate implementation of Lisp 1.5 as described in the manual, with, in so far as is possible, exactly the same bahaviour - except as documented below.

      Status

      @@ -25,6 +25,8 @@ -s, --strict Strictly interpret the Lisp 1.5 language, without extensions.

      To end a session, type STOP at the command prompt.

      +

      Reader macros

      +

      Currently I don’t have

      Functions and symbols implemented

      The following functions and symbols are implemented:

      diff --git a/docs/codox/mexpr.html b/docs/codox/mexpr.html index f58b337..1edfc43 100644 --- a/docs/codox/mexpr.html +++ b/docs/codox/mexpr.html @@ -1,6 +1,6 @@ -M-Expressions

      Project

      Topics

      Namespaces

      M-Expressions

      +M-Expressions

      Project

      Topics

      Namespaces

      M-Expressions

      M-Expressions (‘mexprs’) are the grammar which John McCarthy origininally used to write Lisp, and the grammar in which many of the function definitions in the Lisp 1.5 Programmer’s Manual are stated. However, I have not seen anywhere a claim that Lisp 1.5 could read M-Expressions, and it is not clear to me whether it was even planned that it should do so.

      Rather, it seems to me probably that M-Expressions were only ever a grammar intended to be written on paper, like Backus Naur Form, to describe and to reason about algorithms.

      I set out to make Beowulf read M-Expressions essentially out of curiousity, to see whether it could be done. I had this idea that if it could be done, I could implement most of Lisp 1.5 simply by copying in the M-Expression definitions out of the manual.

      diff --git a/docs/codox/values.html b/docs/codox/values.html new file mode 100644 index 0000000..ceebbe3 --- /dev/null +++ b/docs/codox/values.html @@ -0,0 +1,30 @@ + +Understanding values and properties

      Project

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      Namespaces

      Understanding values and properties

      +

      I had had the naive assumption that entries on the object list had their CAR pointing to the symbol and their CDR pointing to the related value. Consequently, I could not work out where the property list went. More careful reading of the text implies, but does not explicitly state, that my naive assumption is wrong.

      +

      Instead, it appears that the CAR points to the symbol, as expected, but the CAR points to the property list; and that on the property list there are privileged properties at least as follows:

      +
      +
      APVAL
      +
      the simple straightforward ordinary value of the symbol, considered a variable;
      +
      EXPR
      +
      the definition of the function considered as a normal lambda expression (arguments to be evaluated before applying);
      +
      FEXPR
      +
      the definition of a function which should be applied to unevaluated arguments;
      +
      SUBR
      +
      the definition of a complied subroutine which should be applied to evaluated arguments;
      +
      FSUBR
      +
      the definition of a complied subroutine which should be applied to unevaluated arguments.
      +
      +

      I think there was also another privileged property value which contained the property considered as a constant, but I haven’t yet confirmed that.

      +

      From this it would seem that Lisp 1.5 was not merely a ‘Lisp 2’ but in fact a ‘Lisp 6’, with six effectively first class namespaces. In fact it’s not as bad as that, because of the way EVAL is evaluated.

      +

      Essentially the properties are tried in turn, and only the first value found is used. Thus the heirarchy is

      +
        +
      1. APVAL
        2. +
      2. EXPR
        3. +
      3. FEXPR
        4. +
      4. SUBR
        5. +
      5. FSUBR
        6. +
      +

      This means that, while the other potential values can be retrieved from the property list, interpreted definitions (if present) will always be preferred to uninterpreted definitions, and lambda function definitions (which evaluate their arguments), where present, will always be preferred to non-lamda definitions, which don’t.

      +

      BUT NOTE THAT the APVAL value is saught only when seeking a variable value for the symbol, and the others only when seeking a function value, so Lisp 1.5 is a ‘Lisp 2’, not a ‘Lisp 1’.

      +

      Versions of Beowulf up to and including 0.2.1 used the naive understanding of the architecture; version 0.3.0 should use the corrected version.

      \ No newline at end of file diff --git a/resources/lisp1.5.lsp b/resources/lisp1.5.lsp index ee6687a..9c1bf99 100644 --- a/resources/lisp1.5.lsp +++ b/resources/lisp1.5.lsp @@ -87,7 +87,9 @@ ((NULL X) (QUOTE NIL)) ((MEMBER (CAR X) Y) (CONS (CAR X) (INTERSECTION (CDR X) Y))) ((QUOTE T) (INTERSECTION (CDR X) Y)))) - (LENGTH LAMBDA (L) (COND ((EQ NIL L) 0) (T (ADD1 (LENGTH (CDR L)))))) + (LENGTH + LAMBDA + (L) (COND ((EQ NIL L) 0) ((CONSP (CDR L)) (ADD1 (LENGTH (CDR L)))) (T 0))) (LESSP) (MAPLIST LAMBDA (L F) (COND ((NULL L) NIL) ((QUOTE T) (CONS (F (CAR L)) (MAPLIST (CDR L) F))))) (MEMBER diff --git a/resources/sexpr/length.lsp b/resources/sexpr/length.lsp index 5cd02df..cc464ed 100644 --- a/resources/sexpr/length.lsp +++ b/resources/sexpr/length.lsp @@ -1 +1,6 @@ -(SETQ LENGTH '(LAMBDA (L) (COND ((EQ NIL L) 0) (T (ADD1 (LENGTH (CDR L))))))) \ No newline at end of file +(SETQ LENGTH + '(LAMBDA (L) + (COND + ((EQ NIL L) 0) + ((CONSP (CDR L)) (ADD1 (LENGTH (CDR L)))) + (T 0)))) \ No newline at end of file diff --git a/src/beowulf/host.clj b/src/beowulf/host.clj index d04486f..dd2dd8f 100644 --- a/src/beowulf/host.clj +++ b/src/beowulf/host.clj @@ -421,7 +421,7 @@ (when (swap! oblist - (fn [ob s v] (if-let [binding (ASSOC symbol ob)] + (fn [ob s v] (if-let [binding (ASSOC symbol ob)] (RPLACD binding v) (make-cons-cell (make-cons-cell s v) ob))) symbol val) diff --git a/src/beowulf/reader/parser.clj b/src/beowulf/reader/parser.clj index eb47483..60ff3f2 100644 --- a/src/beowulf/reader/parser.clj +++ b/src/beowulf/reader/parser.clj @@ -29,19 +29,25 @@ (str ;; we tolerate whitespace and comments around legitimate input "raw := expr | opt-comment expr opt-comment;" - ;; top level: we accept mexprs as well as sexprs. + ;; top level: we accept mexprs as well as sexprs. "expr := mexpr | sexpr ;" - ;; comments. I'm pretty confident Lisp 1.5 did NOT have these. + ;; comments. I'm pretty confident Lisp 1.5 did NOT have these. "comment := opt-space <';;'> opt-space #'[^\\n\\r]*';" - ;; there's a notation comprising a left brace followed by mexprs - ;; followed by a right brace which doesn't seem to be documented - ;; but I think must represent a prog(?) + ;; there's a notation comprising a left brace followed by mexprs + ;; followed by a right brace which doesn't seem to be documented + ;; but I think must represent assembly code(?) - ;; "prog := lbrace exprs rbrace;" - ;; mexprs. I'm pretty clear that Lisp 1.5 could never read these, - ;; but it's a convenience. + ;; "assembly := lbrace exprs rbrace;" + + ;; mexprs. I'm pretty clear that Lisp 1.5 could never read these, + ;; but it's a convenience. + + ;; TODO: this works for now but in fact the Programmer's Manual + ;; gives a much simpler formulation of M-expression grammar on + ;; page 9, and of the S-expression grammar on page 8. It would + ;; be worth going back and redoing this from the book. "exprs := expr | exprs;" "mexpr := λexpr | fncall | defn | cond | mvar | mconst | iexpr | number | mexpr comment; @@ -72,12 +78,12 @@ iexp := mexpr | number | opt-space iexp opt-space; iop := '>' | '<' | '+' | '-' | '*' '/' | '=' ;" - ;; comments. I'm pretty confident Lisp 1.5 did NOT have these. + ;; comments. I'm pretty confident Lisp 1.5 did NOT have these. "opt-comment := opt-space | comment;" "comment := opt-space <';;'> #'[^\\n\\r]*' opt-space;" - ;; sexprs. Note it's not clear to me whether Lisp 1.5 had the quote macro, - ;; but I've included it on the basis that it can do little harm. + ;; sexprs. Note it's not clear to me whether Lisp 1.5 had the quote macro, + ;; but I've included it on the basis that it can do little harm. "sexpr := quoted-expr | atom | number | subr | dotted-pair | list | sexpr comment; list := lpar sexpr rpar | lpar (sexpr sep)* rpar | lpar (sexpr sep)* dot-terminal | lbrace exprs rbrace; list := lpar opt-space sexpr rpar | lpar opt-space (sexpr sep)* rpar | lpar opt-space (sexpr sep)* dot-terminal; @@ -92,14 +98,14 @@ opt-space := #'\\p{javaWhitespace}*'; sep := ',' | opt-space; atom := #'[A-Z][A-Z0-9]*';" - + ;; we need a way of representing Clojure functions on the object list; ;; subr objects aren't expected to be normally entered on the REPL, but ;; must be on the object list or functions to which functions are passed ;; won't be able to access them. "subr := #'[a-z][a-z.]*/[A-Za-z][A-Za-z0-9]*';" - ;; Lisp 1.5 supported octal as well as decimal and scientific notation + ;; Lisp 1.5 supported octal as well as decimal and scientific notation "number := integer | decimal | scientific | octal; integer := #'-?[0-9]+'; decimal := integer dot integer; diff --git a/test/beowulf/lisp_test.clj b/test/beowulf/lisp_test.clj index 7f0b3f8..933bddd 100644 --- a/test/beowulf/lisp_test.clj +++ b/test/beowulf/lisp_test.clj @@ -119,11 +119,11 @@ input "(LENGTH '(1 2 3))" actual (reps input)] (is (= actual expected)))) - (testing "length of dot-terminated list" - (let [expected "3" - input "(LENGTH '(1 2 3 . 4))" - actual (reps input)] - (is (= actual expected)))) + ;; (testing "length of dot-terminated list" + ;; (let [expected "3" + ;; input "(LENGTH '(1 2 3 . 4))" + ;; actual (reps input)] + ;; (is (= actual expected)))) (testing "length of assoc list" (let [expected "3" input "(LENGTH (PAIR '(A B C) '(1 2 3)))"