Thursday, March 13, 2014


Summary: HLint now has a real API.

HLint is a tool for making suggestions about your Haskell source code, available as a standalone tool (via cabal install hlint) and from several Haskell environments including the FP Complete IDE, Eclipse FP and IHaskell. Until now, HLint has provided an API which took a list of command line arguments, and essentially ran the hlint executable, but in process. With the release of hlint-1.8.59 I've now included a "real" API as Language.Haskell.HLint2. Some features include:

  • You can create your own hint as a Haskell function, using the HLint facilities to apply it to your code.
  • More information is provided about the resulting suggestions, including source spans.
  • The API accepts haskell-src-exts modules, and provides easy ways to parse strings, meaning files are not required and you can use existing syntax trees.
  • Some of the utilities used inside HLint are now available, including liberal name resolution and lenient parsing.

I recommend all users of the old API migrate to the new one, as I intend to phase out the old API in the near future (please let me know if that will cause you any problems). I plan to evolve the new API in response to user feedback, and then in a little while delete the old API, rename HLint2 to HLint, and bump the version number. I welcome feedback on the API, and am always curious to see where HLint gets used.