Fix typechecking with bindings

[scheme.git] / typecheck.scm

diff --git a/typecheck.scm b/typecheck.scm
index c6b90e701f467d1651d87c434441b4305ea98742..f6d7c86465f4869043b3d2fcb9560e42603258d7 100644 (file)
--- 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)]