add basic support for markdownlint

autoload/ale/handlers/markdownlint.vim

@@ -0,0 +1,17 @@
+" Author: Ty-Lucas Kelley <tylucaskelley@gmail.com>
+" Description: Adds support for markdownlint
+
+function! ale#handlers#markdownlint#Handle(buffer, lines) abort
+    let l:pattern=': \(\d*\): \(MD\d\{3}\)\(\/\)\([A-Za-z0-9-]\+\)\(.*\)$'
+    let l:output=[]
+
+    for l:match in ale#util#GetMatches(a:lines, l:pattern)
+        call add(l:output, {
+            \ 'lnum': l:match[1] + 0,
+            \ 'text': '(' . l:match[2] . l:match[3] . l:match[4] . ')' . l:match[5],
+            \ 'type': 'W',
+        \ })
+    endfor
+
+    return l:output
+endfunction