Support for fish file linting

ale_linters/fish/fish.vim

@@ -0,0 +1,36 @@
+" Author: Niraj Thapaliya - https://github.com/nthapaliya
+" Description: Lints fish files using fish -n
+
+function! ale_linters#fish#fish#Handle(buffer, lines) abort
+    " Matches patterns such as:
+    "
+    " home/.config/fish/functions/foo.fish (line 1): Missing end to balance this function definition
+    " function foo
+    " ^
+    " <W> fish: Error while reading file .config/fish/functions/foo.fish
+    let l:pattern = '^.* (line \(\d\+\)): \(.*\)$'
+    let l:output = []
+
+    let l:i = 0
+    while l:i < len(a:lines)
+      let l:match = matchlist(a:lines[l:i], l:pattern)
+      if len(l:match) && len(l:match[2])
+        call add(l:output, {
+              \  'col': len(a:lines[l:i + 2]),
+              \  'lnum': str2nr(l:match[1]),
+              \  'text': l:match[2],
+              \})
+      endif
+      let l:i += 1
+    endwhile
+
+    return l:output
+endfunction
+
+call ale#linter#Define('fish', {
+\   'name': 'fish',
+\   'output_stream': 'stderr',
+\   'executable': 'fish',
+\   'command': 'fish -n %t',
+\   'callback': 'ale_linters#fish#fish#Handle',
+\})