bugfix in stlc+sub: subs assumed length=?

2015-10-15 14:00:42 -04:00 · 2015-10-15 14:00:42 -04:00 · e2b1eaa06b
commit e2b1eaa06b
parent 48b625c2f4
1 changed files with 3 additions and 1 deletions
--- a/tapl/stlc+sub.rkt
+++ b/tapl/stlc+sub.rkt
@ -41,7 +41,9 @@
        (Top? τ2)))
  (define current-sub? (make-parameter sub?))
  (current-typecheck-relation sub?)
-  (define (subs? τs1 τs2) (stx-andmap (current-sub?) τs1 τs2))
+  (define (subs? τs1 τs2)
+    (and (stx-length=? τs1 τs2)
+         (stx-andmap (current-sub?) τs1 τs2)))
  
  (define-syntax (define-sub-relation stx)
    (syntax-parse stx #:datum-literals (<: =>)