Add hackfmt fixer

autoload/ale/fix/registry.vim

@@ -117,6 +117,11 @@ let s:default_registry = {
 \       'suggested_filetypes': ['rust'],
 \       'description': 'Fix Rust files with Rustfmt.',
 \   },
+\   'hackfmt': {
+\       'function': 'ale#fixers#hackfmt#Fix',
+\       'suggested_filetypes': ['php'],
+\       'description': 'Fix Hack files with hackfmt.',
+\   },
 \   'hfmt': {
 \       'function': 'ale#fixers#hfmt#Fix',
 \       'suggested_filetypes': ['haskell'],

autoload/ale/fixers/hackfmt.vim

@@ -0,0 +1,18 @@
+" Author: Sam Howie <samhowie@gmail.com>
+" Description: Integration of hackfmt with ALE.
+
+call ale#Set('php_hackfmt_executable', 'hackfmt')
+call ale#Set('php_hackfmt_options', '')
+
+function! ale#fixers#hackfmt#Fix(buffer) abort
+    let l:executable = ale#Var(a:buffer, 'php_hackfmt_executable')
+    let l:options = ale#Var(a:buffer, 'php_hackfmt_options')
+
+    return {
+    \   'command': ale#Escape(l:executable)
+    \       . ' -i'
+    \       . (empty(l:options) ? '' : ' ' . l:options)
+    \       . ' %t',
+    \   'read_temporary_file': 1,
+    \}
+endfunction