effect-typeclass-design

Define an interface describing the operations for a generic type A, then write functions that take the typeclass instance as the first parameter and curry the remaining arguments. This enables partial application and reuse across any type with an instance.

Use Function.dual from effect/Function with the arity of the data-first form and a single uncurried implementation. It returns an overloaded function supporting both direct calls like f(self, arg) and pipe-friendly calls like pipe(self, f(arg)).

Data-first functions take the data as the first argument for direct calls, while data-last functions take it last so they fit into pipe compositions. Dual APIs expose both forms from one implementation.

Use currying when you need partial application, such as passing isMoreThan(D)(minimum) directly to Array.filter or reusing a configured predicate. It also keeps the typeclass instance as the stable first parameter.

Yes, use Order.mapInput to project an existing Order onto your type through the typeclass accessor, for example Order.mapInput(Duration.Order, D.getDuration) to order values by their duration.