diff --git a/src/Control/Monad/ST2.hs b/src/Control/Monad/ST2.hs --- a/src/Control/Monad/ST2.hs +++ b/src/Control/Monad/ST2.hs @@ -48,7 +48,7 @@ -- -- unshared reference still holds its original value. -- liftL $ do -- check <- readSTRef secret --- return (check == 42) +-- return (check == 42) -- :} module Control.Monad.ST2 ( -- * ST2 API @@ -75,7 +75,7 @@ -- * Unsafe API , toBaseST , fromBaseST - + , STret , unsafeInterleaveST, unsafeDupableInterleaveST , stToPrim @@ -95,6 +95,7 @@ import Data.Eq (Eq((==))) import Data.Function (($), (.)) import Data.Functor (Functor(fmap)) +import Data.Kind (Type) #if !(MIN_VERSION_base(4,11,0)) import Data.Monoid (Monoid(mempty, mappend)) #else @@ -103,12 +104,11 @@ import Data.Semigroup (Semigroup((<>))) import GHC.IO (IO(IO),unsafeDupableInterleaveIO) import GHC.MVar (readMVar, putMVar, newEmptyMVar) -import GHC.Prim (State#, unsafeCoerce#, MutVar#, newMutVar#, readMutVar#, writeMutVar#, sameMutVar#, RealWorld, noDuplicate#) +import GHC.Exts (State#, unsafeCoerce#, MutVar#, newMutVar#, readMutVar#, writeMutVar#, sameMutVar#, RealWorld, noDuplicate#, RuntimeRep, TYPE, Any, isTrue#) import GHC.Show (Show(showsPrec, showList), showString, showList__) -import GHC.Types (RuntimeRep, TYPE, Any, isTrue#) import Theory.Named (type (~~)) import Unsafe.Coerce (unsafeCoerce) -import qualified GHC.Magic as GHCMagic +import qualified GHC.Exts as GHCExts -- | Convert an ST2 to an ST toBaseST :: ST s a -> BaseST.ST s a @@ -140,7 +140,7 @@ -- values stored in the state). For example, -- -- @'runST' (writeSTRef _|_ v >>= f) = _|_@ -newtype ST s a = ST (STRep (Any ~~ s) a) +newtype ST (s :: Type) a = ST (STRep (Any ~~ s) a) -- | Convenience type alias for expressing ST computations -- more succintly. @@ -392,7 +392,7 @@ runRegion# :: forall (r :: RuntimeRep) (o :: TYPE r) s. (State# (Any ~~ s) -> o) -> o -runRegion# m = GHCMagic.runRW# (unsafeCoerce# m) -- m = m (rwToAny# realWorld#) +runRegion# m = GHCExts.runRW# (unsafeCoerce# m) -- m = m (rwToAny# realWorld#) {-# INLINE runRegion# #-} {- Note [runRegion#] @@ -409,44 +409,44 @@ complete. Below, I will inline "Note [runRW magic]" which is written in ghc's compiler/coreSyn/CorePrep.hs: -Some definitions, for instance @runST@, must have careful control over float out -of the bindings in their body. Consider this use of @runST@, - - f x = runST ( \ s -> let (a, s') = newArray# 100 [] s - (_, s'') = fill_in_array_or_something a x s' - in freezeArray# a s'' ) - -If we inline @runST@, we'll get: - - f x = let (a, s') = newArray# 100 [] realWorld#{-NB-} - (_, s'') = fill_in_array_or_something a x s' - in freezeArray# a s'' - -And now if we allow the @newArray#@ binding to float out to become a CAF, -we end up with a result that is totally and utterly wrong: - - f = let (a, s') = newArray# 100 [] realWorld#{-NB-} -- YIKES!!! - in \ x -> - let (_, s'') = fill_in_array_or_something a x s' - in freezeArray# a s'' - -All calls to @f@ will share a {\em single} array! Clearly this is nonsense and -must be prevented. - -This is what @runRW#@ gives us: by being inlined extremely late in the -optimization (right before lowering to STG, in CorePrep), we can ensure that -no further floating will occur. This allows us to safely inline things like -@runST@, which are otherwise needlessly expensive (see #10678 and #5916). - -'runRW' is defined (for historical reasons) in GHC.Magic, with a NOINLINE -pragma. It is levity-polymorphic. - - runRW# :: forall (r1 :: RuntimeRep). (o :: TYPE r) - => (State# RealWorld -> (# State# RealWorld, o #)) - -> (# State# RealWorld, o #) - +Some definitions, for instance @runST@, must have careful control over float out +of the bindings in their body. Consider this use of @runST@, + + f x = runST ( \ s -> let (a, s') = newArray# 100 [] s + (_, s'') = fill_in_array_or_something a x s' + in freezeArray# a s'' ) + +If we inline @runST@, we'll get: + + f x = let (a, s') = newArray# 100 [] realWorld#{-NB-} + (_, s'') = fill_in_array_or_something a x s' + in freezeArray# a s'' + +And now if we allow the @newArray#@ binding to float out to become a CAF, +we end up with a result that is totally and utterly wrong: + + f = let (a, s') = newArray# 100 [] realWorld#{-NB-} -- YIKES!!! + in \ x -> + let (_, s'') = fill_in_array_or_something a x s' + in freezeArray# a s'' + +All calls to @f@ will share a {\em single} array! Clearly this is nonsense and +must be prevented. + +This is what @runRW#@ gives us: by being inlined extremely late in the +optimization (right before lowering to STG, in CorePrep), we can ensure that +no further floating will occur. This allows us to safely inline things like +@runST@, which are otherwise needlessly expensive (see #10678 and #5916). + +'runRW' is defined (for historical reasons) in GHC.Magic, with a NOINLINE +pragma. It is levity-polymorphic. + + runRW# :: forall (r1 :: RuntimeRep). (o :: TYPE r) + => (State# RealWorld -> (# State# RealWorld, o #)) + -> (# State# RealWorld, o #) + It needs no special treatment in GHC except this special inlining -in CorePrep (and in ByteCodeGen). +in CorePrep (and in ByteCodeGen). -} diff --git a/st2.cabal b/st2.cabal --- a/st2.cabal +++ b/st2.cabal @@ -2,7 +2,7 @@ name: st2 version: - 0.1.0.2 + 0.1.1 synopsis: shared heap regions between local mutable state threads description: @@ -14,7 +14,7 @@ memory regions. Within that computation, the user can run sub-computations bound to one or the other memory region. Furthermore, a sub-computation can move any variable that it owns into the common overlap via `share`. - . + . An example is shown in the documentation, where one sub-computation creates two cells: one private, and the other shared. A second sub-computation has unconstrained access to the shared cell. Yet even though the private reference is also in scope during the second @@ -42,11 +42,14 @@ exposed-modules: Control.Monad.ST2 build-depends: - base >= 4.9 && < 4.13 - , gdp >= 0.0.0.1 && < 0.1.0.0 - , ghc-prim - , primitive >= 0.6.4.0 + base >= 4.9 && < 5 + , gdp >= 0.0.0.1 && < 0.1 + , primitive >= 0.6.4 && < 0.8 hs-source-dirs: src default-language: Haskell2010 + +source-repository head + type: git + location: git://github.com/chessai/st2.git