fix bug with sequence

direct-style-interpreter.scm

@@ -8,7 +8,7 @@
 ;; the procedures that create them as combinators
 ;; (note: is this true? don't they still use free variables in their definitions?)
 ;; ((yes, because they are of dynamic scope, therefore not captured))
-
+
 ;; Globals
 (define undefined-value (make-symbol "undefined"))
 (define g.init (make-parameter '()))
@@ -18,7 +18,6 @@
 
 (define sg.init (make-vector 100))
 (define sg.current (make-vector 100))
-
 
 ;; Macros
 (define-syntax with-fresh-globals
@@ -82,7 +81,6 @@
                     (error "Incorrect arity" 'name)))])
       (description-extend! 'name `(function ,value a b c))
       (make-closure behavior (*env*)))))
-
 
 ;; Record types
 (define-record-type <activation-record>
@@ -256,7 +254,6 @@
            (invoke proc rec))
          (error "Wrong arity" 'apply)))
    (*env*)))
-
 
 ;; Denotations
 (define (meaning e r tail?)
@@ -275,8 +272,8 @@
 (define (meaning-quotation e*)
   (CONSTANT e*))
 
-(define (CONSTANT value)
-  (lambda () value))
+(define (CONSTANT v)
+  (lambda () v))
 
 (define (meaning-alternative e1 e2 e3 r tail?)
   (let ([m1 (meaning e1 r #f)]
@@ -288,19 +285,16 @@
   (lambda ()
     (if (m1) (m2) (m3))))
 
-(define (meaning-sequence e* r tail?)
-  (if (null? e*)
-      (static-error "Illegal syntax (begin)")
-      (SEQUENCE (meaning-list e* r tail?))))
+(define (meaning-sequence e+ r tail?)
+  (cond
+   [(null? e+) (static-error "Illegal syntax (begin)")]
+   [(null? (cdr e+)) (meaning (car e+) r tail?)]
+   [else (SEQUENCE (meaning (car e+) r #f)
+                   (meaning-sequence (cdr e+) r tail?))]))
 
-(define (SEQUENCE m+)
+(define (SEQUENCE m m+)
   (lambda ()
-    (let lp ([m* m+])
-      (if (null? (cdr m*))
-          ((car m*))
-          (begin
-            ((car m*))
-            (lp (cdr m*)))))))
+    (m) (m+)))
 
 (define (meaning-reference n r)
   (match (compute-kind n r)
@@ -554,7 +548,6 @@
                  (m+))
           (error "Incorrect arity")))
     (make-closure the-function (*env*))))
-
 
 ;; Tests
 (test-begin "direct-style-interpreter")
@@ -576,8 +569,8 @@
   ;; sequences
 (test-group "meaning-sequence"
   (with-fresh-globals
-   (env-set! '((a b)))
-   (test-eq 'b
+   (env-set! '((1 2)))
+   (test-eq 2
      ((meaning-sequence '(a b) '((a b)) #t)))))
 ;; references
 (test-group "meaning-reference"
@@ -639,7 +632,7 @@
                                (cont v)
                                v)) #f 0)
                        '(()) #t))))
-#;(test-group "apply"
+(test-group "apply"
   (test-eq 3 ((meaning '(apply + 1 2 '()) '(()) #t)))
   (test-eq 3 ((meaning '(apply + '(1 2)) '(()) #t))))
 (test-end "direct-style-interpreter")