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Omit unnecessary parens when pretty-printing IfaceExpr
[ghc-hetmet.git]
/
compiler
/
deSugar
/
DsUtils.lhs
diff --git
a/compiler/deSugar/DsUtils.lhs
b/compiler/deSugar/DsUtils.lhs
index
9a0e752
..
25366fa
100644
(file)
--- a/
compiler/deSugar/DsUtils.lhs
+++ b/
compiler/deSugar/DsUtils.lhs
@@
-419,7
+419,7
@@
But that is bad for two reasons:
Seq is very, very special! So we recognise it right here, and desugar to
case x of _ -> case y of _ -> (# x,y #)
Seq is very, very special! So we recognise it right here, and desugar to
case x of _ -> case y of _ -> (# x,y #)
-Note [Desugaring seq (2)] cf Trac #2231
+Note [Desugaring seq (2)] cf Trac #2273
~~~~~~~~~~~~~~~~~~~~~~~~~
Consider
let chp = case b of { True -> fst x; False -> 0 }
~~~~~~~~~~~~~~~~~~~~~~~~~
Consider
let chp = case b of { True -> fst x; False -> 0 }
@@
-447,10
+447,14
@@
should have said explicitly
But that's painful. So the code here does a little hack to make seq
more robust: a saturated application of 'seq' is turned *directly* into
But that's painful. So the code here does a little hack to make seq
more robust: a saturated application of 'seq' is turned *directly* into
-the case expression. So we desugar to:
+the case expression, thus:
+ x `seq` e2 ==> case x of x -> e2 -- Note shadowing!
+ e1 `seq` e2 ==> case x of _ -> e2
+
+So we desugar our example to:
let chp = case b of { True -> fst x; False -> 0 }
case chp of chp { I# -> ...chp... }
let chp = case b of { True -> fst x; False -> 0 }
case chp of chp { I# -> ...chp... }
-Notice the shadowing of the case binder! And now all is well.
+And now all is well.
The reason it's a hack is because if you define mySeq=seq, the hack
won't work on mySeq.
The reason it's a hack is because if you define mySeq=seq, the hack
won't work on mySeq.
@@
-600,7
+604,7
@@
mkLHsVarPatTup bs = mkLHsPatTup (map nlVarPat bs)
mkVanillaTuplePat :: [OutPat Id] -> Boxity -> Pat Id
-- A vanilla tuple pattern simply gets its type from its sub-patterns
mkVanillaTuplePat pats box
mkVanillaTuplePat :: [OutPat Id] -> Boxity -> Pat Id
-- A vanilla tuple pattern simply gets its type from its sub-patterns
mkVanillaTuplePat pats box
- = TuplePat pats box (mkTupleTy box (length pats) (map hsLPatType pats))
+ = TuplePat pats box (mkTupleTy box (map hsLPatType pats))
-- The Big equivalents for the source tuple expressions
mkBigLHsVarTup :: [Id] -> LHsExpr Id
-- The Big equivalents for the source tuple expressions
mkBigLHsVarTup :: [Id] -> LHsExpr Id