X-Git-Url: http://git.lukelau.me/?a=blobdiff_plain;f=ast.scm;h=b3f21bd07d6d07ba2b64017cff0a365cbf77abd4;hb=006b94f5a24a794665788737fec8d54086284317;hp=9af36531e7ef38bb1affc652eb09c5afa46a3dcc;hpb=86531822ef58c5b29751976f5b41d1c631bdd459;p=scheme.git

diff --git a/ast.scm b/ast.scm
index 9af3653..b3f21bd 100644
--- a/ast.scm
+++ b/ast.scm
@@ -75,23 +75,55 @@
     ['stack (either (p x) (inner (caddr x)))]
     [else (p x)]))
 
-(define (let-bindings e)
-  (define (pattern-match binding body)
-    (if (eqv? (ast-type binding) 'var)
-	(list (cons binding body))
-	(let* ([constructor (car binding)]
-	       [destructor (lambda (i) (dtor-name constructor i))])
-	  (flat-map (lambda (y i)
-		      (pattern-match y `((,(destructor i) ,@body))))
-		    (cdr binding)
-		    (range 0 (length (cdr binding)))))))
-  (flat-map (lambda (x) (pattern-match (car x) (cdr x))) (cadr e)))
+(define let-bindings cadr)
 (define let-body cddr)
 
+					; (let ([(foo a b) (foo 123 345)]) a)
+					;   |
+					;   v
+					; (let ([a (foo~0 (foo 123 345)]
+                                        ;       [b (foo~1 (foo 123 345)]) a)
+(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))]
+		   [products (cdr binding-name)]
+
+		   [data-layouts (program-data-layouts program)]
+
+		   [type (data-tor-type data-layouts sum-name)]
+
+		   [sum (assoc sum-name (cdr (assoc type data-layouts)))]
+		   
+		   [expected-number (length (cdr sum))])
+
+					; 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))))
+			products
+			(range 0 (length products)))))))
+    (case (ast-type x)
+      ['let `(let ,(flat-map pattern-match (let-bindings 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)
@@ -112,12 +144,24 @@
   (filter (lambda (x) (eqv? (statement-type x) 'defines))
 	  program))
 
+(define (program-map-exprs f program)
+  (map (lambda (x)
+	 (case (statement-type x)
+	   ['expr (f x)]
+	   [else x]))
+       program))
+
 (define (program-body program)
   ; hack to have multi-expression bodies
   `(let ()
      ,@(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)