X-Git-Url: https://git.lukelau.me/?p=scheme.git;a=blobdiff_plain;f=ast.scm;h=b70317a70e6fd3a14aa9fab5c94be57991427f2e;hp=8a986173d675f43eb58cd0c5f7c6c7c679175d9f;hb=8e106ca13666680051f91ab3f49ce2bd7e19ead7;hpb=c4a5f8ab1efce20f0e1181ffe34639facb19594a

diff --git a/ast.scm b/ast.scm
index 8a98617..b70317a 100644
--- a/ast.scm
+++ b/ast.scm
@@ -1,3 +1,5 @@
+(load "utils.scm")
+
 (define (ast-type x)
   (define (builtin? x)
     (case x
@@ -33,7 +35,7 @@
     ('app (map f x))
     ('lambda `(lambda ,(lambda-args x) ,(f (lambda-body x))))
     ('if `(if ,@(map f (cdr x))))
-    ('stack `(stack ,(cadr x) ,(map f (caddr x))))
+    ('stack `(stack ,(cadr x) ,(f (caddr x))))
     (else x)))
 
 (define (ast-collect f x)
@@ -83,27 +85,54 @@
 					;   v
 					; (let ([a (foo~0 (foo 123 345)]
                                         ;       [b (foo~1 (foo 123 345)]) a)
-(define (expand-pattern-matches x)  
+(define (expand-pattern-matches program)
+  (define (go x)
     (define (pattern-match binding)
       (let ([binding-name (car binding)]
 	    [body (cadr binding)])
 	(if (eqv? (ast-type binding-name) 'var)
 	    (list (list binding-name body))
+	    
 	    (let* ([sum-name (car binding-name)]
-		 [destructor (lambda (i) (dtor-name sum-name i))])
+		   [destructor (lambda (i) (dtor-name sum-name i))]
+		   [products (cdr binding-name)]
+
+		   [data-layouts (program-data-layouts program)]
+
+		   [type (data-tor-type data-layouts sum-name)]
+
+		   [sums (cdr (assoc type data-layouts))]
+		   [sum (assoc sum-name sums)]
+		   
+		   [expected-number (length (cdr sum))])
+
+					; assert that we only do a let pattern match on an ADT with exactly one sum
+	      (when (not (= 1 (length sums)))
+		(error #f (format "Cannot pattern match a ~a in a let since it has ~a possible constructors"
+				  type
+				  (length sums))))
+
+					; assert that there is the correct number of bindings
+	      (when (not (= (length products)
+			    expected-number))
+		(error #f (format "Got ~a bindings: expected ~a for ~a"
+			       (length products)
+			       expected-number
+			       binding)))
+	      
 	      (flat-map (lambda (y i)
 			  (pattern-match (list y `(,(destructor i) ,body))))
-		      (cdr binding-name)
-		      (range 0 (length (cdr binding-name))))))))
+			products
+			(range 0 (length products)))))))
     (case (ast-type x)
       ['let `(let ,(flat-map pattern-match (let-bindings x))
-	          ,@(map expand-pattern-matches (let-body x)))]
-      [else (ast-traverse expand-pattern-matches x)]))
+	       ,@(map go (let-body x)))]
+      [else (ast-traverse go x)]))
+  (program-map-exprs go program))
 
 (define (lambda? x)
   (and (list? x) (eq? (car x) 'lambda)))
 
-
 (define (statement-type x)
   (cond
    [(and (list? x)
@@ -137,6 +166,11 @@
      ,@(filter (lambda (x) (eqv? (statement-type x) 'expr))
 	       program)))
 
+(define (data-tor-type data-layouts tor)
+  (let* ([tors (flat-map data-tors data-layouts)]
+	 [info (cadr (assoc tor tors))])
+    (car info)))
+
 					; a data tor is either a constructor or destructor for an ADT
 					; data-tors returns constructors and destructors for a data-layout
 					; (data A (foo Int Bool)
@@ -297,26 +331,3 @@
 	   (strong-connect v)))
        (car graph)))
     result))
-
-
-					; utils
-
-(define (range s n)
-  (if (= 0 n) '()
-      (append (range s (- n 1))
-	      (list (+ s (- n 1))))))
-
-(define (flat-map f . xs) (fold-left append '() (apply map (cons f xs))))
-(define (repeat x n) (if (<= n 0) '()
-			 (cons x (repeat x (- n 1)))))
-
-
-(define-syntax push!
-  (syntax-rules ()
-    ((_ s x) (set! s (cons x s)))))
-
-(define-syntax pop!
-  (syntax-rules ()
-    ((_ s) (let ([x (car s)])
-	     (set! s (cdr s))
-	     x))))