Arbitrary stack access. What to do with tail calls?

scmvm/language/scheme.scm

@@ -1,6 +1,9 @@
 (define-module (scmvm language scheme)
   #:use-module (scmvm assembler)
-  #:use-module (ice-9 match))
+  #:use-module (srfi srfi-1)
+  #:use-module (srfi srfi-26)
+  #:use-module (ice-9 match)
+  #:export (compile decompile ir-convert))
 
 ;; Scheme compiler
 ;; Scheme subset we're targeting
@@ -29,7 +32,6 @@
 		(name (cdr v*)
 		      (lambda (t*)
 			(k (cons t t*)))))))))
-
 
 ;; Desugaring
 ;; Transforms to simplify the language
@@ -47,7 +49,7 @@
 
 (define (desugar-prgm prgm)
   (map (lambda (top)
-	 (if (eq? (car top) 'define)
+	 (if (and (pair? top) (eq? (car top) 'define))
 	     (desugar-define top)
 	     (desugar-exp top)))
        prgm))
@@ -94,14 +96,15 @@
 ;; <cexp> ::= (<aexp> <aexp> ...)
 ;;          | (if <aexp> <cexp> <cexp>)
 ;;          | (set-then! <var> <aexp> <cexp>)
+;;          | (define-then! <var> <aexp> <cexp>)
 ;; <aexp> ::= (lambda (<var> ...) exp)
-;;          | <num> | <sym> | <var> | #t | #f
+;;          | <num> | <var> | #t | #f
 ;; 
 ;; We choose a hybrid transformation based on https://matt.might.net/articles/cps-conversion/
 
 (define undefined-value (make-symbol "undefined"))
 
-(define (cps-convert expr ktail)
+(define (cps-convert-prgm prgm ktail)
   ;; M : expr -> aexp
   ;; T-k : expr, (aexp -> cexp) -> cexp
   ;; T-c : expr, aexp -> cexp
@@ -165,17 +168,7 @@
 		 (T*-k e* (lambda ($e*)
 			    `(,$f ,@$e* ,c)))))]))
   (define-cps-loop T*-k T-k)
-  (T-k expr ktail))
+  (T-c prgm ktail))
 
-(define (cps-convert-prgm prgm)
-  (if (pair? prgm)
-      (cons (cps-convert-top (car prgm))
-            (cps-convert-prgm (cdr prgm)))
-      '()))
-
-(define (cps-convert-top top)
-  (match top
-    [`(define ,v ,e)
-     (cps-convert e (lambda ($rv) `(define ,v ,$rv)))]
-    [_
-     (cps-convert top (lambda _ `(nop)))]))
+(define* (ir-convert prgm #:key (ktail 'ktail))
+  (cps-convert-prgm (desugar-prgm prgm) ktail))