Looks similar to how languages with effect systems work. (Or appear to work, I haven't actually sat down with one yet.) They don't capture the exact functions,

Looks similar to how languages with effect systems work. (Or appear to work, I haven't actually sat down with one yet.) They don't capture the exact functions, rather captuing the capabilities of said functions, which are the important bit anyway. The distinction between `print` vs `printline` doesn't matter too much, the fact you're doing `IO` does. It seems to be largely new languages trying this, but I believe there's a few addons for languages such as Haskell as well. https://koka-lang.github.io/koka/doc/index.html https://koka-lang.github.io/koka/doc/index.html https://www.unison-lang.org/docs/fundamentals/abilities/ https://www.unison-lang.org/docs/fundamentals/abilities/ https://dev.epicgames.com/documentation/en-us/uefn/verse-language-reference https://dev.epicgames.com/documentation/en-us/uefn/verse-lan...