std::execution::just - cppreference.com (original) (raw)
A sender factory that returns a sender which completes immediately by calling the receiver’s set_value().
Let ts be a pack of subexpressions. The expression just(ts...) is expression-equivalent to /*make-sender*/(just, /*product-type*/(ts...))
Customization point objects
The name execution::just denotes a customization point object, which is a const function object of a literal semiregular class type. The cv-unqualified version of its type is a tag type denoted as execution::just_t. See CustomizationPointObject for details.