Track effects used by functions

[lpil]

I've had the idea of tracking function purity in my head for some time now, and now I discover that Nim has a similar system!

This prior art will be very useful for designing any future effects tracking in Gleam :)

Links

• Nim: https://nim-lang.org/docs/manual.html#effect-system
• Koka: https://koka-lang.github.io/koka/doc/kokaspec.html

Rough sketch of how it might look in Gleam

https://github.com/gleam-experiments/experiments/blob/master/effects.gleam

[lpil]

An interesting piece of research on coeffects tracking http://tomasp.net/coeffects/

[lpil]

The other day @crowdhailer cleverly noted that it could be useful to track whether functions are async when targetting JavaScript. This could be a use for effects tracking.