add + operator on lists

2013-10-23 15:06:57 -07:00 · 2013-10-23 15:06:57 -07:00 · ce5083fad9
parent 0800608479
commit ce5083fad9
1 changed files with 1 additions and 0 deletions
--- a/interp.hs
+++ b/interp.hs
@ -59,6 +59,7 @@ instance Show Value where
 -- value operators
 (IntV l) +$ (IntV r) = IntV (l + r)
 (StrV l) +$ (StrV r) = StrV (l ++ r)
+(ListV l) +$ (ListV r) = ListV (l ++ r)
 l +$ r = error $ "cannot + " ++ show l ++ " and " ++ show r

 (IntV l) -$ (IntV r) = IntV (l - r)