kumi::monoid Concept Reference

Concept specifying a type is a Monoid
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#include <kumi/utils/concepts.hpp>

Detailed Description

Concept specifying a type is a Monoid

A type T models kumi::monoid if it's a binary associative callable equipped with an identity element acting as the neutral element for that operation.

The identity is defined so that the following property holds for the operation.

monoid(x, indentity) = monoid(identity, x) = x

Note

The operation is not required to be commutative; that is monoid(x,y) and monoid(y,x) may yield different results. (Ie : the monoid is not necessarily abelian)

Concept definition

template<typename T>
concept kumi::monoid =  []()
  {
    using M = std::remove_cvref_t<T>;
    return requires(M m) {
      { M::identity };
      { M{}(M::identity, M::identity) }; 
    };
  }()