Hello, guys.
We have recently created a syntax highlighting for COS for Atom text editor. You can find it on https://github.com/intersystems-ru/atom-language-cos
Installation:
InterSystems ObjectScript is a scripting language to operate with data using any data model of InterSystems Data Platform (Objects, Relational, Key-Value, Document, Globals) and to develop business logic for serverside applications on InterSystems Data Platform.