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| author | Simon Peyton Jones <simonpj@microsoft.com> | 2013-11-22 15:23:22 +0000 |
|---|---|---|
| committer | Simon Peyton Jones <simonpj@microsoft.com> | 2013-11-22 18:59:28 +0000 |
| commit | f438464754ad9abd885acf3529606ca57945edc2 (patch) | |
| tree | e2edaf1078865f544a55153c02bb1906099586c0 /compiler/prelude/PrelNames.lhs | |
| parent | b83666d4813b62b0b2da9b8238af6909c9f1dae0 (diff) | |
| download | haskell-f438464754ad9abd885acf3529606ca57945edc2.tar.gz | |
Replace (State# RealWorld) with Void# where we just want a 0-bit value
We were re-using the super-magical "state token" type (which has
VoidRep and is zero bits wide) for situations in which we simply want
to lambda-abstract over a zero-bit argument. For example, join points:
case (case x of { True -> e1; False -> e2 }) of
Red -> f1
Blue -> True
==>
let $j1 = \voidArg::Void# -> f1
in
case x of
True -> case e1 of
Red -> $j1 void
Blue -> True
False -> case e2 of
Red -> $j1 void
Blue -> True
This patch introduces
* The new primitive type GHC.Prim.Void#, with PrimRep = VoidRep
* A new global Id GHC.Prim.voidPrimId :: Void#.
This has no binding because the code generator drops it,
but is used as an argument (eg in the call of $j1)
* A new local Id, MkId.voidArgId, which can be lambda-bound
when you need to lambda-abstract over it.
and uses them throughout.
Now the State# thing is used only when we need state!
Diffstat (limited to 'compiler/prelude/PrelNames.lhs')
| -rw-r--r-- | compiler/prelude/PrelNames.lhs | 6 |
1 files changed, 4 insertions, 2 deletions
diff --git a/compiler/prelude/PrelNames.lhs b/compiler/prelude/PrelNames.lhs index 6223567451..85da3accb6 100644 --- a/compiler/prelude/PrelNames.lhs +++ b/compiler/prelude/PrelNames.lhs @@ -1357,7 +1357,7 @@ statePrimTyConKey, stableNamePrimTyConKey, stableNameTyConKey, liftedConKey, unliftedConKey, anyBoxConKey, kindConKey, boxityConKey, typeConKey, threadIdPrimTyConKey, bcoPrimTyConKey, ptrTyConKey, funPtrTyConKey, tVarPrimTyConKey, eqPrimTyConKey, - eqReprPrimTyConKey :: Unique + eqReprPrimTyConKey, voidPrimTyConKey :: Unique statePrimTyConKey = mkPreludeTyConUnique 50 stableNamePrimTyConKey = mkPreludeTyConUnique 51 stableNameTyConKey = mkPreludeTyConUnique 52 @@ -1365,6 +1365,7 @@ eqPrimTyConKey = mkPreludeTyConUnique 53 eqReprPrimTyConKey = mkPreludeTyConUnique 54 mutVarPrimTyConKey = mkPreludeTyConUnique 55 ioTyConKey = mkPreludeTyConUnique 56 +voidPrimTyConKey = mkPreludeTyConUnique 57 wordPrimTyConKey = mkPreludeTyConUnique 58 wordTyConKey = mkPreludeTyConUnique 59 word8TyConKey = mkPreludeTyConUnique 60 @@ -1576,7 +1577,7 @@ wildCardKey, absentErrorIdKey, augmentIdKey, appendIdKey, buildIdKey, errorIdKey, foldrIdKey, recSelErrorIdKey, seqIdKey, irrefutPatErrorIdKey, eqStringIdKey, noMethodBindingErrorIdKey, nonExhaustiveGuardsErrorIdKey, - runtimeErrorIdKey, patErrorIdKey, + runtimeErrorIdKey, patErrorIdKey, voidPrimIdKey, realWorldPrimIdKey, recConErrorIdKey, unpackCStringUtf8IdKey, unpackCStringAppendIdKey, unpackCStringFoldrIdKey, unpackCStringIdKey :: Unique @@ -1601,6 +1602,7 @@ unpackCStringUtf8IdKey = mkPreludeMiscIdUnique 17 unpackCStringAppendIdKey = mkPreludeMiscIdUnique 18 unpackCStringFoldrIdKey = mkPreludeMiscIdUnique 19 unpackCStringIdKey = mkPreludeMiscIdUnique 20 +voidPrimIdKey = mkPreludeMiscIdUnique 21 unsafeCoerceIdKey, concatIdKey, filterIdKey, zipIdKey, bindIOIdKey, returnIOIdKey, newStablePtrIdKey, |