Idris2-boot/libs/base/Data/IORef.idr
Edwin Brady 69a7640a6e Allow flagging types as externally defined
e.g. in a C file. This means we don't accidentally treat things as
empty, since previously we just defined these as empty types, but that
broke coverage checking. Fixes #240
2020-04-10 11:45:52 +01:00

37 lines
902 B
Idris

module Data.IORef
%cg chicken (use box)
-- Implemented externally
-- e.g., in Scheme, passed around as a box
data Mut : Type -> Type where [external]
%extern prim__newIORef : forall a . a -> (1 x : %World) -> IORes (Mut a)
%extern prim__readIORef : forall a . Mut a -> (1 x : %World) -> IORes a
%extern prim__writeIORef : forall a . Mut a -> (1 val : a) -> (1 x : %World) -> IORes ()
export
data IORef : Type -> Type where
MkRef : Mut a -> IORef a
export
newIORef : a -> IO (IORef a)
newIORef val
= do m <- primIO (prim__newIORef val)
pure (MkRef m)
export
readIORef : IORef a -> IO a
readIORef (MkRef m) = primIO (prim__readIORef m)
export
writeIORef : IORef a -> (1 val : a) -> IO ()
writeIORef (MkRef m) val = primIO (prim__writeIORef m val)
export
modifyIORef : IORef a -> (a -> a) -> IO ()
modifyIORef ref f
= do val <- readIORef ref
writeIORef ref (f val)