Use a structural approach to type inference#3
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Currently, we use a nominal approach, forcing users to explicitly state (and thus ask us for proof) that some function
Fapplied toAresults inFA. We do so by tracking all the functionsFand their argumentAthat a user has cast a type to. This PR uses a purely structural approach. The typefunctionFis forced to be inferred first. Then, and only then, we magically resolve the constraints onFA, thus verifying that it's indeed equivalent toK<F, A>. This seems to work pretty well, but it's also horribly tricky to get rightTo be honest, I don't remember the exact details of this. It was all written by me, no AI (other than copilot auto-completion), so I'm sure I can work it out again if needed.