[#beman-optional-is_derived_from_optional]
= xref:beman.adoc[beman]::xref:beman/optional.adoc[optional]::is_derived_from_optional
:relfileprefix: ../../
:mrdocs:

== Synopsis

Declared in `<beman/optional/optional.hpp>`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
template<class T>
concept is_derived_from_optional = requires(const T& t) { // exposition only
    []<class U>(const optional<U>&) {}(t);
};
----


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