hlint

Display suggestions for a Haskell file

$ hlint [path/to/file.hs]

$ hlint [path/to/directory] -r

$ hlint [path/to/file.hs] --refactor

$ hlint [path/to/file.hs] --refactor-options

$ hlint [path/to/file.hs] --default > .hlint.yaml

hlint [options] [files]

hlint is a tool for suggesting improvements to Haskell source code. It analyzes code and provides suggestions for simplification, redundancy removal, and style improvements based on common Haskell idioms.
Suggestions include simplifying expressions, removing unnecessary extensions, applying standard library functions, and following best practices. The tool can automatically apply many of its suggestions through the refactor mode.
Configuration files (.hlint.yaml) allow customizing which hints to apply or ignore on a per-project basis.

-r, --report

Generate an HTML report of suggestions

Automatically apply suggestions using refactor tool

Display available refactoring options

Generate default configuration ignoring current hints

Use hints from specified file

Ignore a specific hint

Not all suggestions are appropriate for every codebase. Some hints may conflict with specific coding standards or performance requirements. Always review automated refactoring changes before committing.

hlint was created by Neil Mitchell and first released around 2006. It has become a standard tool in the Haskell ecosystem for maintaining code quality and is commonly integrated into CI pipelines and editor plugins.

ghc(1), cabal(1), stack(1)