hof/doc/src/compose.md

compose

Description

The compose function adaptor provides function composition. It produces a function object that composes a set of functions, ie the output of one function becomes the input of the second function. So, compose(f, g)(0) is equivalent to f(g(0)).

Synopsis

template<class... Fs>
constexpr compose_adaptor<Fs...> compose(Fs... fs);

Requirements

Fs must be:

FunctionObject
MoveConstructible

Example

struct increment
{
    template<class T>
    T operator()(T x) const
    {
        return x + 1;
    }
};

struct decrement
{
    template<class T>
    T operator()(T x) const
    {
        return x - 1;
    }
};

int r = compose(increment(), decrement(), increment())(3);
assert(r == 4);