graphql-engine/server/src-lib/Control/Monad/Stateless.hs
Robert 11a454c2d6 server, pro: actually reformat the code-base using ormolu
This commit applies ormolu to the whole Haskell code base by running `make format`.

For in-flight branches, simply merging changes from `main` will result in merge conflicts.
To avoid this, update your branch using the following instructions. Replace `<format-commit>`
by the hash of *this* commit.

$ git checkout my-feature-branch
$ git merge <format-commit>^    # and resolve conflicts normally
$ make format
$ git commit -a -m "reformat with ormolu"
$ git merge -s ours post-ormolu

https://github.com/hasura/graphql-engine-mono/pull/2404

GitOrigin-RevId: 75049f5c12f430c615eafb4c6b8e83e371e01c8e
2021-09-23 22:57:37 +00:00

27 lines
799 B
Haskell

{-# LANGUAGE UndecidableInstances #-}
module Control.Monad.Stateless
( MonadStateless (..),
)
where
import Control.Monad.Trans.Control
import Data.Type.Equality
import Prelude
class (MonadBaseControl b m, forall a. StatelessProof m a) => MonadStateless b m | m -> b where
liftWithStateless :: ((forall a. m a -> b a) -> b c) -> m c
instance (MonadBaseControl b m, forall a. StatelessProof m a) => MonadStateless b m where
liftWithStateless f = liftBaseWith $ \lowerBase ->
let lowerBasePure :: forall a. m a -> b a
lowerBasePure m = case statelessProof @m @a of
Refl -> lowerBase m
in f lowerBasePure
class (StM m a ~ a) => StatelessProof m a where
statelessProof :: StM m a :~: a
instance (StM m a ~ a) => StatelessProof m a where
statelessProof = Refl