1−{-# LANGUAGE PatternGuards, CPP, ScopedTypeVariables, ViewPatterns #-}
1+{-# LANGUAGE PatternGuards, CPP, ScopedTypeVariables, ViewPatterns, FlexibleContexts #-}
3Copyright (C) 2010-2014 John MacFarlane <jgm@berkeley.edu>
3Copyright (C) 2010-2014 John MacFarlane <jgm@berkeley.edu>