Use elm-format for formatcmd in Elm

rc/filetype/elm.kak

@@ -25,6 +25,11 @@ hook -group elm-highlight global WinSetOption filetype=elm %{
     hook -once -always window WinSetOption filetype=.* %{ remove-highlighter window/elm }
 }
 
+hook global WinSetOption filetype=elm %{
+    set-option window formatcmd 'elm-format --stdin'
+}
+
+
 provide-module elm %[
 
 # Highlighters