`funsig` keyword not colored

[samolego]

Hi there!

First off, thanks for the extension! We're using SML at my university and this comes in really handy!

I'd like to point out that funsig keyword doesn't seem to be "detected" as such.

Here's some uses of it: https://www.smlnj.org/doc/features.html

[omarjatoi]

Hi! Really glad to hear the extension is useful.

Thanks for opening the issue, the underlying cause here is the tree-sitter grammar I'm using for SML (tree-sitter-sml) does not support all the SML/NJ extensions and I believe funsig in one such extension (i.e. not in 'The Definition of Standard ML').

That said, let me see if I can add some kind of override in highlights.scm so the funsig keyword gets highlighted.