Skip to content

Define default for liftBase with liftBaseDefault #18

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Open
Ericson2314 wants to merge 2 commits into
base: master
Choose a base branch
from
Open

Define default for liftBase with liftBaseDefault #18

Changes from all commits
Commits
Show all changes
2 commits
Select commit Hold shift + click to select a range
4722c76
Sort langauge extensions
Ericson2314 Jul 17, 2019
0f239b7
Define default for `liftBase` with `liftBaseDefault`
Ericson2314 Jul 17, 2019
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
14 changes: 9 additions & 5 deletions src/Control/Monad/Base.hs
View file
Open in desktop
Original file line number Diff line number Diff line change
@@ -1,9 +1,11 @@
{-# LANGUAGE CPP #-}
{-# LANGUAGE UnicodeSyntax #-}
{-# LANGUAGE MultiParamTypeClasses #-}
{-# LANGUAGE FunctionalDependencies #-}
{-# LANGUAGE DefaultSignatures #-}
{-# LANGUAGE FlexibleInstances #-}
{-# LANGUAGE FunctionalDependencies #-}
{-# LANGUAGE MultiParamTypeClasses #-}
{-# LANGUAGE TypeFamilies #-}
{-# LANGUAGE UndecidableInstances #-}
{-# LANGUAGE UnicodeSyntax #-}

#if MIN_VERSION_base(4,4,0)
{-# LANGUAGE Safe #-}
Expand Down Expand Up @@ -55,6 +57,8 @@ class (Applicative b, Applicative m, Monad b, Monad m)
⇒ MonadBase b m | m → b where
-- | Lift a computation from the base monad
liftBase ∷ b α → m α
default liftBase :: (m ~ t m', MonadTrans t, MonadBase b m') => b α → m α
liftBase = liftBaseDefault

#define BASE(M) \
instance MonadBase (M) (M) where liftBase = id
Expand Down Expand Up @@ -87,7 +91,7 @@ liftBaseDefault ∷ (MonadTrans t, MonadBase b m) ⇒ b α → t m α
liftBaseDefault = lift . liftBase

#define TRANS(T) \
instance (MonadBase b m) ⇒ MonadBase b (T m) where liftBase = liftBaseDefault
instance (MonadBase b m) ⇒ MonadBase b (T m)

TRANS(IdentityT)
TRANS(MaybeT)
Expand All @@ -101,7 +105,7 @@ TRANS(SelectT r)
#undef TRANS

#define TRANS_CTX(CTX, T) \
instance (CTX, MonadBase b m) ⇒ MonadBase b (T m) where liftBase = liftBaseDefault
instance (CTX, MonadBase b m) ⇒ MonadBase b (T m)

TRANS_CTX(Monoid w, L.WriterT w)
TRANS_CTX(Monoid w, S.WriterT w)
Expand Down