All ready to implement property lists, not yet done.

resources/mexpr/apply-2.mexpr.lsp

@@ -1,21 +0,0 @@
-;; see page 70 of Lisp 1.5 Programmers Manual; this expands somewhat 
-;; on the accounts of eval and apply given on page 13. This is M-expr
-;; syntax, obviously. 
-
-;; apply
-;; NOTE THAT I suspect there is a typo in the printed manual in line
-;; 7 of this definition, namely a missing closing square bracket before
-;; the final semi-colon; that has been corrected here.
-
-apply[fn;args;a] = [
-    null[fn] -> NIL;
-    atom[fn] -> [get[fn;EXPR] -> apply[expr; args; a];
-                 get[fn;SUBR] -> {spread[args];
-                                  $ALIST := a;
-                                  TSX subr4, 4};
-                 T -> apply[cdr[sassoc[fn; a; λ[[]; error[A2]]]]; args a]];
-    eq[car[fn]; LABEL] -> apply[caddr[fn]; args; 
-                                cons[cons[cadr[fn];caddr[fn]]; a]];
-    eq[car[fn]; FUNARG] -> apply[cadr[fn]; args; caddr[fn]];
-    eq[car[fn]; LAMBDA] -> eval[caddr[fn]; nconc[pair[cadr[fn]; args]; a]];
-    T -> apply[eval[fn;a]; args; a]]

resources/mexpr/apply.mexpr.lsp

@@ -0,0 +1,40 @@
+;; see page 70 of Lisp 1.5 Programmers Manual; this expands somewhat 
+;; on the accounts of eval and apply given on page 13. This is M-expr
+;; syntax, obviously. 
+
+;; ## APPLY
+
+;; NOTE THAT I suspect there is a typo in the printed manual in line
+;; 7 of this definition, namely a missing closing square bracket before
+;; the final semi-colon; that has been corrected here. 
+
+;; RIGHT! So the 'EXPR' representation of a function is expected to be
+;; on the `EXPR` property on the property list of the symbol which is 
+;; its name; an expression is simply a Lisp S-Expression as a structure
+;; of cons cells and atoms in memory. The 'SUBR' representation, expected
+;; to be on the `SUBR` property, is literally a subroutine written in 
+;; assembly code, so what is happening in the curly braces is putting the
+;; arguments into processor registers prior to a jump to subroutine - TSX
+;; being presumably equivalent to a 6502's JSR call.
+
+;; This accounts for the difference between this statement and the version
+;; on page 12: that is a pure interpreter, which can only call those host 
+;; functions that are explicitly hard coded in.
+
+;; This version knows how to recognise subroutines and jump to them, but I 
+;; think that by implication at least this version can only work if it is
+;; itself compiled with the Lisp compiler, since the section in curly braces
+;; appears to be intended to be passed to the Lisp assembler.
+
+;; apply[fn;args;a] = [
+;;     null[fn] -> NIL;
+;;     atom[fn] -> [get[fn;EXPR] -> apply[expr; args; a];
+;;                  get[fn;SUBR] -> {spread[args];
+;;                                   $ALIST := a;
+;;                                   TSX subr4, 4};
+;;                  T -> apply[cdr[sassoc[fn; a; λ[[]; error[A2]]]]; args a]];
+;;     eq[car[fn]; LABEL] -> apply[caddr[fn]; args; 
+;;                                 cons[cons[cadr[fn];caddr[fn]]; a]];
+;;     eq[car[fn]; FUNARG] -> apply[cadr[fn]; args; caddr[fn]];
+;;     eq[car[fn]; LAMBDA] -> eval[caddr[fn]; nconc[pair[cadr[fn]; args]; a]];
+;;     T -> apply[eval[fn;a]; args; a]]

resources/mexpr/assoc.mexpr.lsp

@@ -1,7 +1,22 @@
-;; Not present in Lisp 1.5(!)
+;; Page 12 of the manual; this does NOT do what I expect a modern
+;; ASSOC to do!
+
+;; Modern ASSOC would be:
+;; assoc[x; l] = [null[l] -> NIL;
+;;            and[consp[car[l]]; eq[caar[l]; x]] -> cdar[l];
+;;            T -> assoc[x; cdr[l]]]
+
+;; In the Lisp 1.5 statement of ASSOC, there's no account of what should happen
+;; if the key (here `x`) is not present on the association list `a`. It seems 
+;; inevitable that this causes an infinite run up the stack until it fails with
+;; stack exhaustion. Consequently this may be right but I'm not implementing it!
+;; assoc[x; a] = [equal[caar[a]; x] -> car[a];
+;;            T -> assoc[x; cdr[a]]]
+
+;; Consequently, my solution is a hybrid. It returns the pair from the 
+;; association list, as the original does, but it traps the end of list
+;; condition, as a modern solution would.
 
 assoc[x; l] = [null[l] -> NIL;
-            and[consp[car[l]]; eq[caar[l]; x]] -> cdar[l];
+            and[consp[car[l]]; eq[caar[l]; x]] -> car[l];
             T -> assoc[x; cdr[l]]]
-
-;; (ASSOC 'C (PAIR '(A B C D E F) (RANGE 1 6)))

resources/mexpr/pairlis.mexpr.lsp

@@ -0,0 +1,5 @@
+;; page 12
+
+pairlis[x;y;a] = [null[x] -> a;
+                T -> cons[cons[car[x]; car[y]];
+                        pairlis[cdr[x]; cdr[y]; a]]]

resources/mexpr/sublis.mexpr.lsp

@@ -0,0 +1,10 @@
+;; There are two different statements of SUBLIS and SUB2 in the manual, on 
+;; pages 12 and 61 respectively, although they are said to be semantically
+;; equivalent; this is the version from page 12. 
+
+sub2[a; z] = [null[a] -> z;
+            eq[caar[a]; z] -> cdar[a];
+            T -> sub2[cdar[a]; z]]
+
+sublis[a; y] = [atom[y] -> sub2[a; y];
+                T -> cons[]]

resources/mexpr/subst.mexpr.lsp

@@ -0,0 +1,5 @@
+;; page 11
+
+subst[x; y; z] = [equal[y; z] -> x;
+                atom[z] -> z;
+                T -> cons[subst[x; y; car[z]]; subst[x; y; cdr[z]]]]