apply_eval

Header

#include <boost/hof/apply_eval.hpp>

Description

The apply_eval function work like apply, except it calls eval on each of its arguments. Each eval call is always ordered from left-to-right.

Synopsis

template<class F, class... Ts>
constexpr auto apply_eval(F&& f, Ts&&... xs);

Semantics

assert(apply_eval(f)(xs...) == f(eval(xs)...));

Requirements

F must be:

• ConstInvocable

Ts must be:

• EvaluatableFunctionObject

Example

#include <boost/hof.hpp>
#include <cassert>

struct sum_f
{
    template<class T, class U>
    T operator()(T x, U y) const
    {
        return x+y;
    }
};

int main() {
    assert(boost::hof::apply_eval(sum_f(), []{ return 1; }, []{ return 2; }) == 3);
}