Hi,

(A pet project warning!)

I've published an extension for VSCode with a brave
attempt to color-hightlight syntax of Jam language:

https://github.com/mloskot/vscode-boost-jam

This is based on a very basic TextMate language grammar
definitions, often naive, and, by no means, it is complete or bug-free
coverage of the Jam. Even so, I think it quite helps to  de-annoy
or even enjoy process of writing Jam scrips :-)

I'm no expert of writing TextMate language grammars
- this is my first ever attempt - so chances are I may be incapable
of fixing bugs or improving it with advanced features.
Especially, that "the process of writing a TextMate language
grammar remains poorly documented"
- http://www.apeth.com/nonblog/stories/textmatebundle.html