Fix CodingStyle#Warnings URLs

[ghc-hetmet.git] / compiler / stranal / DmdAnal.lhs

diff --git a/compiler/stranal/DmdAnal.lhs b/compiler/stranal/DmdAnal.lhs
index 309cd29..a939907 100644 (file)
--- a/compiler/stranal/DmdAnal.lhs
+++ b/compiler/stranal/DmdAnal.lhs
@@ -7,6 +7,13 @@
                        -----------------
 
 \begin{code}
+{-# OPTIONS -w #-}
+-- The above warning supression flag is a temporary kludge.
+-- While working on this module you are encouraged to remove it and fix
+-- any warnings in the module. See
+--     http://hackage.haskell.org/trac/ghc/wiki/Commentary/CodingStyle#Warnings
+-- for details
+
 module DmdAnal ( dmdAnalPgm, dmdAnalTopRhs, 
                 both {- needed by WwLib -}
    ) where
@@ -43,11 +50,13 @@ import UniqFM               ( plusUFM_C, addToUFM_Directly, lookupUFM_Directly,
 import Type            ( isUnLiftedType, coreEqType, splitTyConApp_maybe )
 import Coercion         ( coercionKind )
 import CoreLint                ( showPass, endPass )
-import Util            ( mapAndUnzip, mapAccumL, mapAccumR, lengthIs )
+import Util            ( mapAndUnzip, lengthIs )
 import BasicTypes      ( Arity, TopLevelFlag(..), isTopLevel, isNeverActive,
                          RecFlag(..), isRec )
 import Maybes          ( orElse, expectJust )
 import Outputable
+
+import Data.List
 \end{code}
 
 To think about
@@ -262,8 +271,8 @@ dmdAnal sigs dmd (Case scrut case_bndr ty [alt@(DataAlt dc,bndrs,rhs)])
        -- The insight is, of course, that a demand on y is a demand on the
        -- scrutinee, so we need to `both` it with the scrut demand
 
-        scrut_dmd         = Eval (Prod [idNewDemandInfo b | b <- bndrs', isId b])
-                                  `both`
+       alt_dmd            = Eval (Prod [idNewDemandInfo b | b <- bndrs', isId b])
+        scrut_dmd         = alt_dmd `both`
                             idNewDemandInfo case_bndr'
 
        (scrut_ty, scrut') = dmdAnal sigs scrut_dmd scrut
@@ -489,7 +498,12 @@ If we marked r as having the CPR property, then we'd w/w into
        in ...
 
 But now r is a thunk, which won't be inlined, so we are no further ahead.
+But consider
+
+       f x = let r = case expensive of (a,b) -> (b,a)
+             in if foo r then r else (x,x)
 
+Does f have the CPR property?  Well, no.
 
 However, if the strictness analyser has figured out (in a previous 
 iteration) that it's strict, then we DON'T need to forget the CPR info.
@@ -986,7 +1000,7 @@ lub d1@(Eval _) d2           = d2 `lub` d1 -- Bot,Abs,Top,Call,Defer
 lub (Box d1)   (Box d2) = box (d1 `lub` d2)
 lub d1@(Box _)  d2     = d2 `lub` d1
 
-lubs = zipWithDmds lub
+lubs ds1 ds2 = zipWithDmds lub ds1 ds2
 
 ---------------------
 -- box is the smart constructor for Box
@@ -1093,7 +1107,7 @@ both d1@(Eval ds1) d2            = d2 `both` d1
 both (Defer ds1) (Defer ds2) = deferEval (ds1 `boths` ds2)
 both d1@(Defer ds1) d2      = d2 `both` d1
  
-boths = zipWithDmds both
+boths ds1 ds2 = zipWithDmds both ds1 ds2
 \end{code}