In my experience Claude is quite good at the popular stacks in the JavaScript, Python and PHP world. It struggled quite a bit when I asked it non-trivial questions in C or Rust for example. For smaller languages (e.g., Crystal) it seems to hallucinate a lot. I think since a lot of people work in JS, Python and PHP, that’s where Claude is very valuable and that’s where a lot of the praise feel justified too.

I have had no problems with using Claude on large rust projects. The compiler errors usually point it towards fixing its mistakes (just like they do for me).

Feed it Crystal documentation and example code. That is what I did with more obscure programming languages and it worked out well in the end.