writer_tag

Synopsis

template <class M>
struct writer_tag
{
  // unspecified
};

Description

This tag represents the Writer monad. M represents the tag of the state. monoid<M> is expected to be defined.

#include <mpllibs/metamonad/writer_tag.hpp>

Expression semantics

The following are equivalent

tag_tag
writer_tag::tag
writer_tag
writer_tag::type

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