Formats Haskell import lists.

It produces import lists that look like this:

import Range.Shared.Types
  ( ExternalRef(..), Imports(Imports), SomeExternalRef(SomeExternalRef), SpecEntity(..)
  , SpecRef(SpecRefExternal, SpecRefLocal), ExternalEntities, IsSpecEntity, ResolvedSpec
  , SpecEntities, VmRepetitionGroup, VmRgTag, importsConfigModuleDefs, importsOperatingSystems
  , importsVmTemplates, specEntitiesConfigModuleDefs, specEntitiesOperatingSystems
  , specEntitiesVmTemplates, specEntity, specificationEntities
  )

SimFormat reads from stdin and writes to stdout. It should always succeed: if it cannot find any import blocks, it will simply pass the text on unchanged.

$ stack install

From within Emacs, assuming you have the haskell-mode and stylish-haskell packages installed and working, (setq haskell-mode-stylish-haskell-path "simformat") and (setq haskell-stylish-on-save t) should automatically reformat your import list on every save. This is completely impossible in Vim, and @asivitz should by no means take this as a personal challenge.

If you prefer not to run code on save, you can use shell-command-on-region with a region active and the prefix argument set, i.e. C-u M-| simformat

From within Vim, e.g., visual select your code (or the whole file) and then run :!simformat