Curry.md

<CppML/Functional/Curry.hpp>

Curry

template <typename F>
struct Curry {
  template <typename ...Ts>
  using f = /* .... */;
};

Curry<F>

Let F be a metafunction Args... -> Us.... Than Curry<F> is a metafunction that takes a parameter pack T0s..., and returns a metafunction F': T1s... -> Us..., in such a way, that F(T0s..., T1s...) == F'(T1s...).

f:: T0s... -> T1s... -> Us...

NOTE

This is similar to ml::CurryR, with the order of the parameter packs T0s... and T1s... switched.

Example

We can create a metafunction that checks if alignment of a type T is greater than alignment of some other type U, by taking ml::Map of ml::AlignOf that has ml::Less as Pipe, and curry it on the left with U (note the order of arguments).

using Maker = ml::Curry<
                ml::Map<
                    ml::AlignOf<>,
                    ml::Less<>>>;

using IsMoreThanInt = ml::f<Maker, int>;
using IsMoreThanChar = ml::f<Maker, char>;

using T0 = ml::f<IsMoreThanInt, float>;
using T1 = ml::f<IsMoreThanChar, float>;
static_assert(
        std::is_same_v<
                T0, ml::Bool<false>>);
static_assert(
        std::is_same_v<
                T1, ml::Bool<true>>);