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Use explicit language extensions & remove extension fields from base.cabal
[ghc-base.git]
/
GHC
/
ST.lhs
diff --git
a/GHC/ST.lhs
b/GHC/ST.lhs
index
8642bbb
..
dc62000
100644
(file)
--- a/
GHC/ST.lhs
+++ b/
GHC/ST.lhs
@@
-1,5
+1,5
@@
\begin{code}
\begin{code}
-{-# OPTIONS_GHC -fno-implicit-prelude #-}
+{-# LANGUAGE NoImplicitPrelude, MagicHash, UnboxedTuples, Rank2Types #-}
{-# OPTIONS_HADDOCK hide #-}
-----------------------------------------------------------------------------
-- |
{-# OPTIONS_HADDOCK hide #-}
-----------------------------------------------------------------------------
-- |
@@
-20,15
+20,14
@@
module GHC.ST where
import GHC.Base
import GHC.Show
import GHC.Base
import GHC.Show
-import GHC.Num
default ()
\end{code}
%*********************************************************
default ()
\end{code}
%*********************************************************
-%* *
+%* *
\subsection{The @ST@ monad}
\subsection{The @ST@ monad}
-%* *
+%* *
%*********************************************************
The state-transformer monad proper. By default the monad is strict;
%*********************************************************
The state-transformer monad proper. By default the monad is strict;
@@
-69,9
+68,9
@@
instance Monad (ST s) where
(ST m) >>= k
= ST (\ s ->
(ST m) >>= k
= ST (\ s ->
- case (m s) of { (# new_s, r #) ->
- case (k r) of { ST k2 ->
- (k2 new_s) }})
+ case (m s) of { (# new_s, r #) ->
+ case (k r) of { ST k2 ->
+ (k2 new_s) }})
data STret s a = STret (State# s) a
data STret s a = STret (State# s) a
@@
-84,7
+83,7
@@
liftST (ST m) = \s -> case m s of (# s', r #) -> STret s' r
unsafeInterleaveST :: ST s a -> ST s a
unsafeInterleaveST (ST m) = ST ( \ s ->
let
unsafeInterleaveST :: ST s a -> ST s a
unsafeInterleaveST (ST m) = ST ( \ s ->
let
- r = case m s of (# _, res #) -> res
+ r = case m s of (# _, res #) -> res
in
(# s, r #)
)
in
(# s, r #)
)
@@
-95,13
+94,13
@@
unsafeInterleaveST (ST m) = ST ( \ s ->
fixST :: (a -> ST s a) -> ST s a
fixST k = ST $ \ s ->
let ans = liftST (k r) s
fixST :: (a -> ST s a) -> ST s a
fixST k = ST $ \ s ->
let ans = liftST (k r) s
- STret _ r = ans
+ STret _ r = ans
in
case ans of STret s' x -> (# s', x #)
instance Show (ST s a) where
showsPrec _ _ = showString "<<ST action>>"
in
case ans of STret s' x -> (# s', x #)
instance Show (ST s a) where
showsPrec _ _ = showString "<<ST action>>"
- showList = showList__ (showsPrec 0)
+ showList = showList__ (showsPrec 0)
\end{code}
Definition of runST
\end{code}
Definition of runST
@@
-111,16
+110,16
@@
SLPJ 95/04: Why @runST@ must not have an unfolding; consider:
\begin{verbatim}
f x =
runST ( \ s -> let
\begin{verbatim}
f x =
runST ( \ s -> let
- (a, s') = newArray# 100 [] s
- (_, s'') = fill_in_array_or_something a x s'
- in
- freezeArray# a s'' )
+ (a, s') = newArray# 100 [] s
+ (_, s'') = fill_in_array_or_something a x s'
+ in
+ freezeArray# a s'' )
\end{verbatim}
If we inline @runST@, we'll get:
\begin{verbatim}
f x = let
\end{verbatim}
If we inline @runST@, we'll get:
\begin{verbatim}
f x = let
- (a, s') = newArray# 100 [] realWorld#{-NB-}
- (_, s'') = fill_in_array_or_something a x s'
+ (a, s') = newArray# 100 [] realWorld#{-NB-}
+ (_, s'') = fill_in_array_or_something a x s'
in
freezeArray# a s''
\end{verbatim}
in
freezeArray# a s''
\end{verbatim}
@@
-131,8
+130,8
@@
f = let
(a, s') = newArray# 100 [] realWorld#{-NB-} -- YIKES!!!
in
\ x ->
(a, s') = newArray# 100 [] realWorld#{-NB-} -- YIKES!!!
in
\ x ->
- let (_, s'') = fill_in_array_or_something a x s' in
- freezeArray# a s''
+ let (_, s'') = fill_in_array_or_something a x s' in
+ freezeArray# a s''
\end{verbatim}
All calls to @f@ will share a {\em single} array! End SLPJ 95/04.
\end{verbatim}
All calls to @f@ will share a {\em single} array! End SLPJ 95/04.
@@
-150,7
+149,7
@@
runST st = runSTRep (case st of { ST st_rep -> st_rep })
-- I'm only letting runSTRep be inlined right at the end, in particular *after* full laziness
-- That's what the "INLINE [0]" says.
-- I'm only letting runSTRep be inlined right at the end, in particular *after* full laziness
-- That's what the "INLINE [0]" says.
--- SLPJ Apr 99
+-- SLPJ Apr 99
-- {-# INLINE [0] runSTRep #-}
-- SDM: further to the above, inline phase 0 is run *before*
-- {-# INLINE [0] runSTRep #-}
-- SDM: further to the above, inline phase 0 is run *before*
@@
-161,5
+160,5
@@
runST st = runSTRep (case st of { ST st_rep -> st_rep })
{-# NOINLINE runSTRep #-}
runSTRep :: (forall s. STRep s a) -> a
runSTRep st_rep = case st_rep realWorld# of
{-# NOINLINE runSTRep #-}
runSTRep :: (forall s. STRep s a) -> a
runSTRep st_rep = case st_rep realWorld# of
- (# _, r #) -> r
+ (# _, r #) -> r
\end{code}
\end{code}