Make bindings visible while a guard is evaluated.

The current implementation repeats the bindings twice, but I guess it's
fine. It seems to work.

2 files changed, 15 insertions, 5 deletions

diff --git a/match-test.csc b/match-test.csc
index bbecce4..31e7afa 100644
--- a/match-test.csc
+++ b/match-test.csc
@@ -74,5 +74,14 @@
     (match 'b
       ((! 'a) 1)
       ((! 'b) (when #f) 2)
-      ((! 'b) 3)
+      ((! 'b) (when #t) 3)
       (_ 4))))
+
+
+(test match-when-depending-on-pattern-variable
+  (assert-equal
+    2
+    (match 10
+      (n (when (= 1 n)) 1)
+      (n (when (= 10 n)) 2)
+      (_ 3))))
diff --git a/match.csc b/match.csc
index d188349..3e02937 100644
--- a/match.csc
+++ b/match.csc
@@ -42,15 +42,16 @@
     (define-syntax match
       (syntax-rules (when)
         ((match x (pattern (when condition) result result* ...))
-         (if (and (matches? x pattern)
-                  condition)
-           (bind-pattern x pattern result result* ...)))
+         (if (matches? x pattern)
+           (bind-pattern x pattern
+             (if condition
+               (begin result result* ...)))))
         ((match x (pattern result1 result2 ...))
          (if (matches? x pattern)
            (bind-pattern x pattern result1 result2 ...)))
         ((match x (pattern (when condition) result result* ...) clause clause* ...)
          (if (and (matches? x pattern)
-                  condition)
+                  (bind-pattern x pattern condition))
            (bind-pattern x pattern result result* ...)
            (match x clause clause* ...)))
         ((match x (pattern result1 result2 ...) clause1 clause2 ...)