Comma-separated extensions

[ulysses4ever]

Better to add commas in the list of extensions for easier copy-pasting to home assignments. Page 9 of slides for lecture 1.

{-# LANGUAGE 
    DataKinds,
    GADTs,
    TypeOperators,
    TypeFamilies,
    RankNTypes,
    ConstraintKinds,
    MultiParamTypeClasses,
    UndecidableInstances,
    StandaloneDeriving,
    ScopedTypeVariables,
    PolyKinds,
    FlexibleInstances,
    FlexibleContexts,
    DefaultSignatures #-}