Ormolu is a formatter for Haskell source code.
The project was created with the following goals in mind:
- 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 each particular
situation 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.
- That formatting style aims to result in minimal diffs while still
remaining very close to “conventional” Haskell formatting people
use.
- 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.
- Be well-tested and robust to the point that it can be used in large
projects without exposing unfortunate, disappointing bugs here and
there.
