Ban use of ==# or ==? in the codebase, and prefer is# or is? instead

ale_linters/haskell/hlint.vim

@@ -5,9 +5,9 @@ function! ale_linters#haskell#hlint#Handle(buffer, lines) abort
     let l:output = []
 
     for l:error in ale#util#FuzzyJSONDecode(a:lines, [])
-        if l:error.severity ==# 'Error'
+        if l:error.severity is# 'Error'
             let l:type = 'E'
-        elseif l:error.severity ==# 'Suggestion'
+        elseif l:error.severity is# 'Suggestion'
             let l:type = 'I'
         else
             let l:type = 'W'