[project @ 2003-12-16 14:27:31 by simonpj]

comments only

diff --git a/ghc/compiler/coreSyn/CoreUtils.lhs b/ghc/compiler/coreSyn/CoreUtils.lhs
index 67d1610..5111730 100644 (file)
--- a/ghc/compiler/coreSyn/CoreUtils.lhs
+++ b/ghc/compiler/coreSyn/CoreUtils.lhs
@@ -793,6 +793,11 @@ arityType (App f a)           = case arityType f of
                                                           
        -- Case/Let; keep arity if either the expression is cheap
        -- or it's a 1-shot lambda
+       -- The former is not really right for Haskell
+       --      f x = case x of { (a,b) -> \y. e }
+       --  ===>
+       --      f x y = case x of { (a,b) -> e }
+       -- The difference is observable using 'seq'
 arityType (Case scrut _ alts) = case foldr1 andArityType [arityType rhs | (_,_,rhs) <- alts] of
                                  xs@(AFun one_shot _) | one_shot -> xs
                                  xs | exprIsCheap scrut          -> xs