* :lang haskell

This module adds [[https://www.haskell.org/][Haskell]] support.

+ Code completion (~company-ghc~)
+ Look up documentation (~hoogle~)
+ eldoc support (~dante~)
+ REPL (~ghci~)
+ Syntax-checking (~flycheck~)
+ Code navigation (~dante~)
+ [[https://github.com/hlissner/emacs-snippets/tree/master/haskell-mode][Snippets]]

#+begin_quote
Haskell contends with C and Ruby as my favorite language. I don't think my Haskell code will ever save the world, but I'll reach for it when working on smaller projects and programming exercises (like projecteuler.com or exercism.io).

I'd love to incorporate more of it into my machine learning work, but Python and Julia hold that crown. For now.
#+end_quote

** Install
To get started with Haskell, you need:

+ cabal (the haskell package builder)
+ ghc/ghci (the compiler, syntax checker & repl)

*** MacOS
#+BEGIN_SRC sh :tangle (if (doom-system-os 'macos) "yes")
brew install cabal-install ghc
#+END_SRC

*** Arch Linux
#+BEGIN_SRC sh :dir /sudo:: :tangle (if (doom-system-os 'arch) "yes")
sudo pacman --needed --noconfirm -S cabal-install ghc
#+END_SRC

** Dependencies
This module requires the following ~cabal~ packages:

+ ~happy~ (required by ~haskell-src-exts~)
+ ~haskell-src-exts~ (required by ~ghc-mod~ & ~hoogle~)
+ ~ghc-mod~ (for auto-completion)
+ ~hoogle~ (for documentation lookup)

#+BEGIN_SRC sh
cabal update
cabal install happy haskell-src-exts ghc-mod hoogle
#+END_SRC

Ensure that ~\~/.cabal/bin~ is in ~PATH~:

#+BEGIN_SRC sh
# place this in your profile file, like ~/.bash_profile or ~/.zshenv
export PATH="~/.cabal/bin:$PATH"
#+END_SRC

** Troubleshooting
+ Stack users: if a ~dist/setup-config~ file exists in your project, [[ https://github.com/DanielG/ghc-mod/wiki#known-issues-related-to-stack][ghc-mod may
  refuse to work]].

** Resources
Here are a few resources I've found indespensible in my Haskell adventures:

+ [[http://learnyouahaskell.com/][Learn you a haskell for great good]]
+ [[http://haskellbook.com/][Haskell Programming from first principles]]
+ [[https://github.com/krispo/awesome-haskell][Awesome Haskell]]: an extensive list of haskell resources