Added command-line flags, some of which actually work.

README.md

@@ -7,10 +7,62 @@ LISP 1.5 is to all Lisp dialects as Beowulf is to Emglish literature.
 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; the only intended deviation is that the parser reads
-'mexprs' (meta language expressions) as well as sexprs.
+same bahaviour - except as documented below.
 
-## BUT WHY?!!?!
+### Status
+
+Boots to REPL, but few functions yet available.
+
+### Architectural plan
+
+Not everything documented in this section is yet built. It indicates the
+direction of travel and intended destination, not the current state.
+
+#### resources/lisp1.5.lsp
+
+The objective is to have within `resources/lisp1.5.lsp`, all those functions
+defined in the Lisp 1.5 Programmer's Manual which can be implemented in Lisp.
+
+This means that, while Beowulf is hosted on Clojure, all that would be
+required to rehost Lisp 1.5 on a different platform would be to reimplement
+
+* bootstrap.clj
+* host.clj
+* read.clj
+
+#### beowulf/boostrap.clj
+
+This file is essentially 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.
+
+In addition it contains the function `INTEROP`, which allows host language
+functions to be called from Lisp.
+
+#### beowulf/host.clj
+
+This file 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.
+
+#### beowulf/read.clj
+
+This file 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. It treats everything between a semi-colon and an end of line as a comment,
+    as most modern Lisps do; but I do not believe Lisp 1.5 had this feature.
+
+
+### BUT WHY?!!?!
 
 Because.
 
@@ -25,7 +77,11 @@ Because I'm barking mad, and this is therapy.
 
 ## Installation
 
-Download from http://example.com/FIXME.
+At present, clone the source and build it using
+
+`lein uberjar`.
+
+You will require to have [Leiningen](https://leiningen.org/) installed.
 
 ## Usage
 

project.clj

@@ -1,10 +1,11 @@
-(defproject beowulf "0.1.0-SNAPSHOT"
+(defproject beowulf "0.2.0-SNAPSHOT"
   :description "An implementation of LISP 1.5 in Clojure"
   :url "http://example.com/FIXME"
   :license {:name "GPL-2.0-or-later"
             :url "https://www.eclipse.org/legal/epl-2.0/"}
-  :dependencies [[org.clojure/clojure "1.10.0"]
+  :dependencies [[org.clojure/clojure "1.8.0"]
                  [org.clojure/math.numeric-tower "0.0.4"]
+                 [org.clojure/tools.cli "0.4.2"]
                  [org.clojure/tools.trace "0.7.10"]
                  [environ "1.1.0"]
                  [instaparse "1.4.10"]]

src/beowulf/bootstrap.clj

@@ -1,7 +1,17 @@
-(ns beowulf.eval
+(ns beowulf.bootstrap
   (:require [clojure.tools.trace :refer :all]
             [beowulf.cons-cell :refer [make-beowulf-list make-cons-cell NIL T F]]))
 
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+;;;
+;;; This file is essentially 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.
+;;;
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+
 (declare EVAL)
 
 (def oblist
@@ -9,6 +19,10 @@
   be Lisp 1.5's EQuivalent of `SETQ`), possibly by other things."
   (atom NIL))
 
+(def ^:dynamic *trace?*
+  "Whether or not to trace `EVAL`."
+  false)
+
 (defn NULL
   [x]
   (if (= x NIL) 'T 'F))
@@ -208,7 +222,7 @@
     :else
     (make-cons-cell (SUBLIS a (CAR y)) (SUBLIS a (CDR y)))))
 
-(deftrace APPLY
+(defn APPLY
   "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."
@@ -217,6 +231,8 @@
     (=
       (ATOM? function)
       'T)(cond
+           ;; TODO: doesn't check whether `function` is bound in the environment;
+           ;; we'll need that before we can bootstrap.
            (= function 'CAR) (CAAR args)
            (= function 'CDR) (CDAR args)
            (= function 'CONS) (make-cons-cell (CAR args) (CADR args))
@@ -261,11 +277,8 @@
       (EVAL (CAR args) env)
       (EVLIS (CDR args) env))))
 
-
-(deftrace EVAL
-  "For bootstrapping, at least, a version of EVAL 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."
+(deftrace traced-eval
+  "Essentially, identical to EVAL except traced."
   [expr env]
   (cond
     (=
@@ -285,3 +298,29 @@
             (EVLIS (CDR expr) env)
             env)))
 
+(defn EVAL
+  "For bootstrapping, at least, a version of EVAL 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."
+  [expr env]
+  (cond
+    *trace?* (traced-eval expr env)
+    (=
+      (ATOM? expr) 'T)
+    (CDR (ASSOC expr env))
+    (=
+      (ATOM? (CAR expr))
+      'T)(cond
+           (= (CAR expr) 'QUOTE) (CADR expr)
+           (= (CAR expr) 'COND) (EVCON (CDR expr) env)
+           :else (APPLY
+                   (CAR expr)
+                   (EVLIS (CDR expr) env)
+                   env))
+    :else (APPLY
+            (CAR expr)
+            (EVLIS (CDR expr) env)
+            env)))
+
+
+

src/beowulf/core.clj

@@ -1,21 +1,35 @@
 (ns beowulf.core
-  (:require [beowulf.eval :refer [EVAL oblist]]
+  (:require [beowulf.bootstrap :refer [EVAL oblist *trace?*]]
             [beowulf.read :refer [READ]]
+            [clojure.java.io :as io]
             [clojure.pprint :refer [pprint]]
+            [clojure.tools.cli :refer [parse-opts]]
             [environ.core :refer [env]])
   (:gen-class))
 
+(def cli-options
+  [["-h" "--help"]
+   ["-p PROMPT" "--prompt PROMPT" "Set the REPL prompt to PROMPT"
+    :default "Sprecan::"]
+   ["-r INITFILE" "--read INITFILE" "Read Lisp functions from the file INITFILE"
+    :validate [#(and
+                  (.exists (io/file %))
+                  (.canRead (io/file %)))
+               "Could not find initfile"]]
+   ["-s" "--strict" "Strictly interpret the Lisp 1.5 language, without extensions."]
+   ["-t" "--trace" "Trace Lisp evaluation."]])
+
 (defn repl
   "Read/eval/print loop."
-  []
+  [prompt]
   (loop []
-    (print "Sprecan:: ")
+    (print prompt)
     (flush)
     (try
       (let [input (read-line)]
         (cond
-          (= input "quit") (throw (ex-info "Færwell!" {:cause :quit}))
-          input (println (str ">  " (EVAL (READ input) @oblist)))
+          (= input "quit") (throw (ex-info "\nFærwell!" {:cause :quit}))
+          input (println (str ">  " (print-str (EVAL (READ input) @oblist))))
           :else (println)))
       (catch
         Exception
@@ -32,22 +46,31 @@
     (recur)))
 
 (defn -main
-  [& args]
-  (println
-    (str
-      "Hider wilcuman. Béowulf is mín nama\nSíðe "
-      (System/getProperty "beowulf.version")
-      "\n\n"))
-  (try
-    (repl)
-    (catch
-      Exception
-      e
-      (let [data (ex-data e)]
+  [& opts]
+  (let [args (parse-opts opts cli-options)]
+    (println
+      (str
+        "\nHider wilcuman. Béowulf is mín nama.\n"
         (if
-          data
-          (case (:cause data)
-            :quit nil
-            ;; default
-            (pprint data))
-          (println e))))))
+          (System/getProperty "beowulf.version")
+          (str "Síðe " (System/getProperty "beowulf.version") "\n"))
+        (if
+          (:help (:options args))
+          (:summary args))
+        (if (:errors args)
+          (apply str (interpose "; " (:errors args))))
+        "\nSprecan 'quit' tó laéfan\n"))
+    (binding [*trace?* (true? (:trace (:options args)))]
+      (try
+        (repl (str (:prompt (:options args)) " "))
+        (catch
+          Exception
+          e
+          (let [data (ex-data e)]
+            (if
+              data
+              (case (:cause data)
+                :quit nil
+                ;; default
+                (pprint data))
+              (println e))))))))

src/beowulf/host.clj

@@ -0,0 +1,9 @@
+(ns beowulf.host)
+
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+;;;
+;;; This file 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.
+;;;
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

src/beowulf/read.clj

@@ -2,9 +2,15 @@
   (:require [clojure.math.numeric-tower :refer [expt]]
             [clojure.string :refer [starts-with? upper-case]]
             [instaparse.core :as i]
-            [beowulf.cons-cell :refer [make-beowulf-list make-cons-cell NIL]])
-;;  (:import [beowulf.cons-cell ConsCell])
-  )
+            [beowulf.cons-cell :refer [make-beowulf-list make-cons-cell NIL]]))
+
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+;;;
+;;; This file 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.
+;;;
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 
 (declare generate)
 

test/beowulf/bootstrap_test.clj

@@ -2,7 +2,7 @@
   (:require [clojure.math.numeric-tower :refer [abs]]
             [clojure.test :refer :all]
             [beowulf.cons-cell :refer [make-beowulf-list make-cons-cell NIL T F]]
-            [beowulf.eval :refer :all]
+            [beowulf.bootstrap :refer :all]
             [beowulf.read :refer [gsp]]))
 
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