Bad requirement of MultiParamTypeClasses

[cblp]

{-# LANGUAGE FlexibleContexts #-}

module Test where

import Control.Monad.Reader

test :: MonadReader a m => m a
test = undefined

This code is OK for GHC, but stylish-haskell requires additional MultiParamTypeClasses.

The error is Language.Haskell.Stylish.Parse.parseModule: could not parse a.hs: ParseFailed (SrcLoc "<unknown>.hs" 7 28) "MultiParamTypeClasses language extension is not enabled. Please add {-# LANGUAGE MultiParamTypeClasses #-} pragma at the top of your module."

UPD. Depends on haskell-suite/haskell-src-exts#304

[jaspervdj]

This is a haskell-src-exts issue.

[cblp]

I opened corresponding haskell-suite/haskell-src-exts#304

[cblp]

For user, this is a bug in stylish-haskell, because (1) it doesn't do what it promised and (2) it was stylish-haskell's author who decided to use haskell-src-exts as a parser.

[cblp]

Thank you for reopening.

[infinity0]

See here for a workaround