validate fix: eliminate a warning

[ghc-hetmet.git] / compiler / deSugar / DsExpr.lhs

diff --git a/compiler/deSugar/DsExpr.lhs b/compiler/deSugar/DsExpr.lhs
index 0633717..b823437 100644 (file)
--- a/compiler/deSugar/DsExpr.lhs
+++ b/compiler/deSugar/DsExpr.lhs
@@ -505,10 +505,8 @@ dsExpr (HsBinTick ixT ixF e) = do
 
 \begin{code}
 
 
 \begin{code}
 

-#ifdef DEBUG

 -- HsSyn constructs that just shouldn't be here:
 dsExpr (ExprWithTySig _ _)  = panic "dsExpr:ExprWithTySig"
 -- HsSyn constructs that just shouldn't be here:
 dsExpr (ExprWithTySig _ _)  = panic "dsExpr:ExprWithTySig"

-#endif

 
 
 findField :: [HsRecField Id arg] -> Name -> [arg]
 
 
 findField :: [HsRecField Id arg] -> Name -> [arg]

@@ -541,13 +539,18 @@ fruitless allocations.  Essentially, whenever we see a list literal
    
    If fusion fails to occur then build will get inlined and (since we
    defined a RULE for foldr (:) []) we will get back exactly the
    
    If fusion fails to occur then build will get inlined and (since we
    defined a RULE for foldr (:) []) we will get back exactly the

-   normal desugaring for an explicit list! However, if it does occur
-   then we can potentially save quite a bit of allocation (up to 25\%
-   of the total in some nofib programs!)
+   normal desugaring for an explicit list.
+
+This optimisation can be worth a lot: up to 25% of the total
+allocation in some nofib programs. Specifically
+
+        Program           Size    Allocs   Runtime  CompTime
+        rewrite          +0.0%    -26.3%      0.02     -1.8%
+           ansi          -0.3%    -13.8%      0.00     +0.0%
+           lift          +0.0%     -8.7%      0.00     -2.3%

 
 Of course, if rules aren't turned on then there is pretty much no
 point doing this fancy stuff, and it may even be harmful.
 
 Of course, if rules aren't turned on then there is pretty much no
 point doing this fancy stuff, and it may even be harmful.

-

 \begin{code}
 
 dsExplicitList :: PostTcType -> [LHsExpr Id] -> DsM CoreExpr
 \begin{code}
 
 dsExplicitList :: PostTcType -> [LHsExpr Id] -> DsM CoreExpr