Open Source Haskell Source Code Management Software

A simple Haskell code prettifier. The goal is not to format all of the code in a file since I find that kind of tools often "get in the way". However, manually cleaning up import statements, etc. gets tedious very quickly. This tool tries to help where necessary without getting in the way. Aligns and sorts import statements. Groups and wraps {-# LANGUAGE #-} pragmas, can remove (some) redundant pragmas. Removes trailing whitespace. Aligns branches in case and fields in records. Converts line endings (customizable) Replaces tabs by four spaces (turned off by default) Replaces some ASCII sequences by their Unicode equivalents (turned off by default) Format data constructors and fields in records.

Ormolu is a formatter for Haskell source code. Using GHC's own parser to avoid parsing problems caused by haskell-src-exts. Let some whitespace be programmable. The layout of the input influences the layout choices in the output. This means that the choices between single-line/multi-line layouts in certain situations are made by the user, not by an algorithm. This makes the implementation simpler and leaves some control to the user while still guaranteeing that the formatted code is stylistically consistent. Writing code in such a way so it's easy to modify and maintain. Implementing one “true” formatting style which admits no configuration. The formatting style aims to result in minimal diffs. Choose a style compatible with modern dialects of Haskell. As new Haskell extensions enter broad use, we may change the style to accommodate them. Idempotence: formatting already formatted code doesn't change it.