X-Git-Url: http://git.lukelau.me/?p=scheme.git;a=blobdiff_plain;f=ast.scm;h=8a986173d675f43eb58cd0c5f7c6c7c679175d9f;hp=9af36531e7ef38bb1affc652eb09c5afa46a3dcc;hb=c4a5f8ab1efce20f0e1181ffe34639facb19594a;hpb=86531822ef58c5b29751976f5b41d1c631bdd459

diff --git a/ast.scm b/ast.scm
index 9af3653..8a98617 100644
--- a/ast.scm
+++ b/ast.scm
@@ -75,19 +75,31 @@
     ['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 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))])
+	    (flat-map (lambda (y i)
+			(pattern-match (list y `(,(destructor i) ,body))))
+		      (cdr binding-name)
+		      (range 0 (length (cdr binding-name))))))))
+  (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)]))
+
 (define (lambda? x)
   (and (list? x) (eq? (car x) 'lambda)))
 
@@ -112,6 +124,13 @@
   (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 ()