Ormolu is a formatter for Haskell source aiming to write code in such
a way so it's easy to modify and maintain. It implements one ?true?
formatting style which admits no configuration, result in minimal
diffs and is compatible with modern dialects of Haskell.  Ormolu is
well-tested and robust so that the formatter can be used in large
projects.

WWW: https://github.com/tweag/ormolu