Add support for fatou (#5159)

Add a linter that runs the fatou language server (`fatou lsp`) for Julia
diagnostics, and a fixer that formats Julia with `fatou format`.

autoload/ale/fix/registry.vim

@@ -124,6 +124,11 @@ let s:default_registry = {
 \       'suggested_filetypes': ['erlang'],
 \       'description': 'Format Erlang code with erlfmt',
 \   },
+\   'fatou': {
+\       'function': 'ale#fixers#fatou#Fix',
+\       'suggested_filetypes': ['julia'],
+\       'description': 'Format Julia files with fatou.',
+\   },
 \   'fecs': {
 \       'function': 'ale#fixers#fecs#Fix',
 \       'suggested_filetypes': ['javascript', 'css', 'html'],

autoload/ale/fixers/fatou.vim

@@ -0,0 +1,15 @@
+" Author: Johan Larsson <johan@jolars.co>
+" Description: Format Julia files with fatou.
+
+call ale#Set('julia_fatou_executable', 'fatou')
+call ale#Set('julia_fatou_options', '')
+
+function! ale#fixers#fatou#Fix(buffer) abort
+    let l:executable = ale#Var(a:buffer, 'julia_fatou_executable')
+    let l:options = ale#Var(a:buffer, 'julia_fatou_options')
+
+    return {
+    \   'command': ale#Escape(l:executable) . ' format'
+    \       . ale#Pad(l:options),
+    \}
+endfunction