A modern programming language that makes developers happier.

kotlinlang

I’m thinking about creating a tool that would promote a more functional approach in certain contexts, like forbid using `var` or  `for` loops (mutability in general), with a way to opt out in certain cases. Think: a step towards more pure FP. I’m wondering if you’d be keen to use it and, if yes, what approach you’d suggest to implement it. I’m thinking about a <https://github.com/detekt/detekt|detekt> rule or a compiler plugin that would emit an error or a warning (configurable)

There is this project from <https://github.com/neeffect/kure-potlin>, but I don't have any experience with it.

It already does some things you mentioned, but ultimately a compiler plugin would be best but I would wait until K2 is stable.

With compiler plugins you can analyse code more deeply, and you can do more advanced things. Like Arrow-analysis, or provide refactor suggestions to auto-fix impure code to pure code, etc. With IDEA support like red-lines explaining why certain patterns should be avoided.