From c89aa1be195b85317ac79845c06586be06c6921f Mon Sep 17 00:00:00 2001
From: Stephen Chang <stchang@ccs.neu.edu>
Date: Fri, 18 Mar 2016 11:57:46 -0400
Subject: [PATCH] fix expected-ty propagation in cond else; closes #3

---
 tapl/mlish.rkt              | 2 +-
 tapl/tests/mlish/inst.mlish | 4 ++++
 2 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/tapl/mlish.rkt b/tapl/mlish.rkt
index 508d515..18ee4ae 100644
--- a/tapl/mlish.rkt
+++ b/tapl/mlish.rkt
@@ -482,7 +482,7 @@
    #:when (same-types? #'(ty_body ...))
    #:with τ_out (stx-car #'(ty_body ...))
    #:with [last-body- last-ty] (if (attribute else_body)
-                                   (infer+erase #'else_body)
+                                   (infer+erase #'(add-expected else_body ty-expected))
                                    (infer+erase #'(void)))
    #:with ([last-b- last-b-ty] ...) (if (attribute else_body)
                                    (infers+erase #'(else_b ...))
diff --git a/tapl/tests/mlish/inst.mlish b/tapl/tests/mlish/inst.mlish
index 21ff08c..f507370 100644
--- a/tapl/tests/mlish/inst.mlish
+++ b/tapl/tests/mlish/inst.mlish
@@ -32,3 +32,7 @@
   (h))
 
 (check-type i : (→/test (Result Int String)))
+
+(define (f/cond [b : Bool] -> (Result Int String))
+  (cond [b (ok 1)]
+        [else (ok 0)]))