find-cycles - analyse dependency cycles in Haskell source code

Usage

Generate .hie files

Use the GHC option -fwrite-ide-info

For more information on generating .hie files, see this GHC blog post

Process .hie files with find-cycles

See nix run github:lawcho/find-cycles#ghc927 -- --help

View generated .html files

e.g. with firefox

No web server needed.

Troubleshooting

"hie file versions don't match" error

find-cycles must be compiled with the same GHC version that generated the .hie files.

Update the #ghcXXX part of your nix build or nix run invocation.

For more information on the backwards-(in)compatability of .hie files, see this GHC ticket

nix run .#ghcXXX is slow for some values of XXX

For versions of GHC without packages cached online in nixpkgs, nix must recompile all the Haskell depndencies of find-cycles from scratch.

You can pre-compile a batch of several versions with nix build .#ghcXXX .#ghcYYY .#ghcZZZ ...

After this completes, nix run will be instant for those versions.

Development

nix build .#ghcXXX type-checks & compiles with GHC version XXX