Extension MultiParameterTypeClasses required by stylish-haskell but not by ghc

Hi, on top of my file I had the language options:

``` haskell
{-# LANGUAGE DataKinds, FlexibleContexts #-}
{-# LANGUAGE OverloadedLabels, ScopedTypeVariables, TypeFamilies #-}
{-# LANGUAGE TypeOperators, UndecidableInstances #-}
```

For a file which compiled with `ghc`. However, stylish-haskell refuses to format the code unless I add also the option `MultiParamTypeClasses`. This is confusing because the file compiles fine, and in emacs when I try to format it just says that `stylish-haskell` found some errors in the buffer.

Why does this happen? How are the implied extensions processed?