I’ve just implemented this in master, allowing implicits in arbitrary scopes, and it’ll be in the next hackage release. It’s not well tested yet though! I have at least tried the following simple examples, and a few others: appShow : Show a => ({b : _} -> Show b => b -> String) -> a … Read more
ST is a monad in which a limited type of side effects are allowed, namely mutable references and mutable arrays. Thus it allows you to implement functions which are pure as seen from the outside world, but which use mutation internally. This is different from State, which only fakes mutation by threading the state through … Read more
It’s hard to understand higher-rank polymorphism unless you study System F directly, because Haskell is designed to hide the details of that from you in the interest of simplicity. But basically, the rough idea is that polymorphic types don’t really have the a -> b form that they do in Haskell; in reality, they look … Read more