Add hdevtools linter for haskell

This adds support for the hdevtools haskell linter
https://github.com/hdevtools/hdevtools

The output for hdevtools is near identical to the ghc output so this
also extracts the ghc handler into the handle file and adds tests

ale_linters/haskell/ghc.vim

@@ -5,63 +5,12 @@ if exists('g:loaded_ale_linters_haskell_ghc')
     finish
 endif
 
-let g:loaded_ale_linters_haskell_ghc = 1
-
-function! ale_linters#haskell#ghc#Handle(buffer, lines) abort
-    " Look for lines like the following.
-    "
-    " /dev/stdin:28:26: Not in scope: `>>>>>'
-    let l:pattern = '^[^:]\+:\(\d\+\):\(\d\+\): \(.\+\)$'
-    let l:output = []
-
-    " For some reason the output coming out of the GHC through the wrapper
-    " script breaks the lines up in strange ways. So we have to join some
-    " lines back together again.
-    let l:corrected_lines = []
-
-    for l:line in a:lines
-        if len(matchlist(l:line, l:pattern)) > 0
-            call add(l:corrected_lines, l:line)
-            if l:line !~# ': error:$'
-                call add(l:corrected_lines, '')
-            endif
-        elseif l:line ==# ''
-            call add(l:corrected_lines, l:line)
-        else
-            if len(l:corrected_lines) > 0
-                let l:line = substitute(l:line, '\v\s+', ' ', '')
-                let l:corrected_lines[-1] .= l:line
-            endif
-        endif
-    endfor
-
-    for l:line in l:corrected_lines
-        let l:match = matchlist(l:line, l:pattern)
-
-        if len(l:match) == 0
-            continue
-        endif
-
-        call add(l:output, {
-        \   'bufnr': a:buffer,
-        \   'lnum': l:match[1] + 0,
-        \   'vcol': 0,
-        \   'col': l:match[2] + 0,
-        \   'text': l:match[3],
-        \   'type': 'E',
-        \   'nr': -1,
-        \})
-    endfor
-
-    return l:output
-endfunction
-
 call ale#linter#Define('haskell', {
 \   'name': 'ghc',
 \   'output_stream': 'stderr',
 \   'executable': 'ghc',
 \   'command': 'ghc -fno-code -v0 %t',
-\   'callback': 'ale_linters#haskell#ghc#Handle',
+\   'callback': 'ale#handlers#HandleGhcFormat',
 \})
 
 call ale#linter#Define('haskell', {
@@ -69,5 +18,5 @@ call ale#linter#Define('haskell', {
 \   'output_stream': 'stderr',
 \   'executable': 'stack',
 \   'command': 'stack ghc -- -fno-code -v0 %t',
-\   'callback': 'ale_linters#haskell#ghc#Handle',
+\   'callback': 'ale#handlers#HandleGhcFormat',
 \})

ale_linters/haskell/hdevtools.vim

@@ -0,0 +1,9 @@
+" Author: w0rp <devw0rp@gmail.com>
+" Description: hdevtools for Haskell files
+
+call ale#linter#Define('haskell', {
+\   'name': 'hdevtools',
+\   'executable': 'hdevtools',
+\   'command': 'hdevtools check -g -Wall -p %s %t',
+\   'callback': 'ale#handlers#HandleGhcFormat',
+\})