X-Git-Url: http://git.lukelau.me/?p=scheme.git;a=blobdiff_plain;f=typecheck.scm;h=f6d7c86465f4869043b3d2fcb9560e42603258d7;hp=c6b90e701f467d1651d87c434441b4305ea98742;hb=f4b0d5c1b14a1890e1b88398e256b272595346b2;hpb=a457cd3bb5ce9366db3ca0731a07abc50ecbc1f3

diff --git a/typecheck.scm b/typecheck.scm
index c6b90e7..f6d7c86 100644
--- a/typecheck.scm
+++ b/typecheck.scm
@@ -191,6 +191,20 @@
 (define (check-case dls env x)
 
   (define (check-match switch-type x)
+    
+    (define (get-bindings product-types pattern)
+      (define (go product-type product)
+	(case (ast-type product)
+	  ['var (list (cons product product-type))]
+					; an inner pattern match
+	  ['app (let* ([inner-sum (car product)]
+		       [inner-sums (cdr (assoc product-type dls))]
+		       [inner-product-types (cdr (assoc inner-sum inner-sums))])
+		  (get-bindings inner-product-types product))]
+	  [else '()]))
+      (flat-map go product-types (cdr pattern)))
+
+    
     (let ([pattern (car x)]
 	  [expr (cadr x)])
       (case (ast-type pattern)
@@ -199,8 +213,9 @@
 	  (let ([sum (assoc (car pattern) (cdr (assoc switch-type dls)))])
 	    (unless sum (error #f "can't pattern match ~a with ~a" switch-type pattern))
 	    (let* ([names (cdr pattern)]
-		   [types (cdr sum)]
-		   [new-env (fold-left env-insert env names types)])
+		   [product-types (cdr sum)]
+		   [new-env (append (get-bindings product-types pattern) env)])
+
 	      (check dls new-env expr)))]
 					; pattern match with binding and no constructor
 	['var (check dls (env-insert env pattern switch-type) expr)]