fix-imports: Program to manage the imports of a haskell module

fix-imports is a small standalone program to manage the import block of a haskell program. It will try to add import lines for qualified names with no corresponding import, remove unused import lines, and keep the import block sorted, with optional rules for grouping.

Support for unqualified imports is limited to symbols you explicitly configure, so if you list System.FilePath ((</>)), it will add that import when you use it, or remove when it's no longer used, but it won't go search modules for unqualified imports.

It doesn't mess with non-managed unqualified imports, so you can still use unqualified imports, you just have to do it manually.

Since it's a unix-style filter, it should be possible to integrate into any editor. There's an example vimrc to bind to a key in vim.

Usage:

Normally you would integrate it with your editor (see vimrc for a vim example), but for testing, here's an example invocation:

fix-imports -i src -i test src/A/B/C.hs <src/A/B/C.hs
[ fixed contents of A/B/C.hs, or an error ]

The -i flag is like ghc's -i flag, it will add an aditional root to the module search path. The example will find modules in both test/* and src/*, in addition to the package db.

fix-imports will look for .ghc.environment.* in the current directory and use it for pkgs to search. This is created by cabal v2, but only if you have write-ghc-environment-files: always in cabal.project. Otherwise, it assumes cabal v1 and will use the ghc-pkg command to use the global package db.

If it doesn't seem to see packages you think it should, run with --debug to see what it sees.

I don't use stack, but my understanding is this is enough to get ghc-pkg working:

export GHC_PACKAGE_PATH=$(stack path --ghc-package-path)