Visual Studio Code is an interesting offering from Microsoft. I feel that the intention is for them to grow it as a cross platform alterative to Visual Studio itself. Perhaps even to potentially replace Visual Studio itself in the longer term. However currently on windows, unless you have a system very low on resources, Visual Studio is by far a better option.

Having co-written a COS plugin for Visual Studio (www.EnsPlus.com) I have explored the possibility of adapting this to VS Code, mainly for the cross platform support. As Jon pointed out you could get it to interact with cache, even without the Atlier Rest API's, since it it is a database and getting data in and out is what it's designed for. 

No, the main difficulty with implementing COS language support for VS Code is, as Timur indicated above, the language parsing.  We spent a lot of time on the parsing using Antlr, the same as intersystems does. ObjectScript is a complicated language and for good quality IDE support it needs the code to be parsed with quite a reasonably high level of detail. 

So far it has not been possible to port our Visual Studio Extension across to VS Code, since our current extension is C# and the VS Code language extensions are currently written in Javascript.

Jeff Sinclair
www.EnsPlus.com