nvim: Use a custom stack compiler for Haskell

Neovim has a "stack" compiler file but this does not seem to work,
at least not in the shitty monorepo I am working on. Someone provided a
solution on Reddit which uses a custom compiler file and has been
modified to work on modules. Which is also perhaps why it doesn't work
in the monorepo project at work.

https://www.reddit.com/r/neovim/comments/es8wn7/haskell_makeprg_for_stack_build/
https://github.com/maxigit/vimrc/tree/2020/compiler

Use them and tie it up with Neomake! change.

Signed-off-by: Sanchayan Maity <maitysanchayan@gmail.com>

nvim/.config/nvim/compiler/ghci.vim

@@ -0,0 +1,20 @@
+" Vim compiler file
+" Compiler: Haskell repl - ghci
+" Author: Maxime Bourget
+
+if exists("current_compiler")
+  finish
+endif
+let current_compiler="ghci"
+" inherit from stack settings
+" compiler stack
+ 
+let s:cpo_save = &cpo
+set cpo&vim
+
+CompilerSet makeprg=stack\ repl
+
+CompilerSet errorformat+=%f:%.%l%.%c%.%#
+
+let &cpo = s:cpo_save
+unlet s:cpo_save

nvim/.config/nvim/compiler/stack.vim

@@ -0,0 +1,42 @@
+" Vim compiler file
+" Compiler:         Haskell Stack
+" Maintainer:       Daniel Campoverde <alx@sillybytes.net>
+" Latest Revision:  2018-08-27
+
+if exists("current_compiler")
+  finish
+endif
+let current_compiler = "stack"
+
+let s:cpo_save = &cpo
+set cpo&vim
+
+
+CompilerSet errorformat=
+    \%-G%.%#:\ build\ %.%#,
+    \%-G%.%#:\ configure\ %.%#,
+    \%-G[%.%#]%.%#,
+    \%-G%.%#preprocessing\ %.%#,
+    \%-G%.%#configuring\ %.%#,
+    \%-G%.%#building\ %.%#,
+    \%-G%.%#linking\ %.%#,
+    \%-G%.%#installing\ %.%#,
+    \%-G%.%#registering\ %.%#,
+    \%-G%.%#:\ copy/register%.%#,
+    \%-G%.%#process\ exited\ %.%#,
+    \%-G%.%#--builddir=%.%#,
+    \%-G--%.%#,
+    \%-G%.%#\|%.%#,
+    \%E%o\ %#>%f:%l:%c:\ error:,%+Z\ \ \ \ %m,
+    \%E%o\ %#>%f:%l:%c:\ error:\ %m,%-Z,
+    \%W%o\ %#>%f:%l:%c:\ warning:,%+Z\ \ \ \ %m,
+    \%W%o\ %#>%f:%l:%c:\ warning:\ %m,%-Z,
+    \%E%f:%l:%c:\ error:,%+Z\ \ \ \ %m,
+    \%E%f:%l:%c:\ error:\ %m,%-Z,
+    \%W%f:%l:%c:\ warning:,%+Z\ \ \ \ %m,
+    \%W%f:%l:%c:\ warning:\ %m,%-Z,
+
+CompilerSet makeprg=stack\ --no-terminal
+
+let &cpo = s:cpo_save
+unlet s:cpo_save

nvim/.config/nvim/init.vim

@@ -386,7 +386,11 @@ augroup END
 
 augroup haskell_maps
     au!
-	au FileType haskell nmap <LocalLeader>b  :NeomakeSh stack build<CR>
+	" https://www.reddit.com/r/neovim/comments/es8wn7/haskell_makeprg_for_stack_build/
+	" https://github.com/maxigit/vimrc/tree/2020/compiler
+	au FileType haskell compiler stack
+	au FileType haskell setlocal makeprg=stack\ build
+	au FileType haskell nmap <LocalLeader>b  :Neomake!<CR>
 	au FileType haskell nmap <LocalLeader>t  :NeomakeSh stack exec -- hasktags -x -c .<CR>
 	au FileType haskell nmap <LocalLeader>g  :Ghcid<CR>
 	au FileType haskell nmap <LocalLeader>k  :GhcidKill<CR>