107 lines
2.3 KiB
Idris
107 lines
2.3 KiB
Idris
module Quox.ST
|
|
|
|
import Data.IORef
|
|
import Control.MonadRec
|
|
|
|
|
|
export
|
|
Tag : Type
|
|
Tag = () -- shhh don't tell anyone
|
|
|
|
export
|
|
record ST (s : Tag) a where
|
|
constructor MkST
|
|
action : IO a
|
|
%name ST st
|
|
|
|
export
|
|
runST : (forall s. ST s a) -> a
|
|
runST st = unsafePerformIO (st {s = ()}).action
|
|
|
|
export %inline Functor (ST s) where map f st = MkST $ map f st.action
|
|
|
|
export %inline
|
|
Applicative (ST s) where
|
|
pure = MkST . pure
|
|
f <*> x = MkST $ f.action <*> x.action
|
|
|
|
export %inline Monad (ST s) where m >>= k = MkST $ m.action >>= action . k
|
|
|
|
export %inline
|
|
MonadRec (ST s) where
|
|
tailRecM s (Access r) x k = MkST $ do
|
|
let MkST yy = k s x
|
|
case !yy of
|
|
Done y => pure y
|
|
Cont s2 p y => let MkST z = tailRecM s2 (r s2 p) y k in z
|
|
|
|
|
|
public export
|
|
interface HasST (0 m : Tag -> Type -> Type) where
|
|
liftST : ST s a -> m s a
|
|
|
|
export %inline HasST ST where liftST = id
|
|
|
|
export
|
|
record STRef (s : Tag) a where
|
|
constructor MkSTRef
|
|
ref : IORef a
|
|
%name STRef r
|
|
|
|
export %inline
|
|
newRef : HasST m => a -> m s (STRef s a)
|
|
newRef x = liftST $ MkST $ MkSTRef <$> newIORef x
|
|
|
|
export %inline
|
|
readRef : HasST m => STRef s a -> m s a
|
|
readRef r = liftST $ MkST $ readIORef r.ref
|
|
|
|
export %inline
|
|
writeRef : HasST m => STRef s a -> a -> m s ()
|
|
writeRef r x = liftST $ MkST $ writeIORef r.ref x
|
|
|
|
export %inline
|
|
modifyRef : HasST m => STRef s a -> (a -> a) -> m s ()
|
|
modifyRef r f = liftST $ MkST $ modifyIORef r.ref f
|
|
|
|
|
|
public export
|
|
record STErr e (s : Tag) a where
|
|
constructor STE
|
|
fromSTErr : ST s (Either e a)
|
|
|
|
export
|
|
Functor (STErr e s) where
|
|
map f (STE e) = STE $ map f <$> e
|
|
|
|
export
|
|
Applicative (STErr e s) where
|
|
pure x = STE $ pure $ pure x
|
|
STE f <*> STE x = STE [|f <*> x|]
|
|
|
|
export
|
|
Monad (STErr e s) where
|
|
STE m >>= k = STE $ do
|
|
case !m of
|
|
Left err => pure $ Left err
|
|
Right x => fromSTErr $ k x
|
|
|
|
export
|
|
MonadRec (STErr e s) where
|
|
tailRecM s (Access r) x k = STE $ do
|
|
let STE m = k s x
|
|
case !m of
|
|
Left err => pure $ Left err
|
|
Right (Cont s' p y) => fromSTErr $ tailRecM s' (r s' p) y k
|
|
Right (Done y) => pure $ Right y
|
|
|
|
export
|
|
runSTErr : (forall s. STErr e s a) -> Either e a
|
|
runSTErr ste = runST $ fromSTErr ste
|
|
|
|
export %inline HasST (STErr e) where liftST = STE . map Right
|
|
|
|
export
|
|
stLeft : e -> STErr e s a
|
|
stLeft e = STE $ pure $ Left e
|