directive

# `meta_non_terminal/1`

## Description

    meta_non_terminal(Template)
    meta_non_terminal((Template, ...))
    meta_non_terminal([Template, ...])

    meta_non_terminal(Entity::Template)
    meta_non_terminal((Entity::Template, ...))
    meta_non_terminal([Entity::Template, ...])

    meta_non_terminal(Module:Template)
    meta_non_terminal((Module:Template, ...))
    meta_non_terminal([Module:Template, ...])

Declares meta-non-terminals, i.e., non-terminals that have arguments that will be called as non-terminals (or grammar rule bodies). An argument may also be a closure instead of a goal if the non-terminal uses the call//1-N Logtalk built-in methods to construct and call the actual non-terminal from the closure and the additional arguments.

Meta-arguments which are non-terminals are represented by the integer `0`. Meta-arguments which are closures are represented by a positive integer, `N`, representing the number of additional arguments that will be appended to the closure in order to construct the corresponding meta-call. Normal arguments are represented by the atom `*`. Meta-arguments are always called in the meta-non-terminal calling context, not in the meta-non-terminal definition context.

## Template and modes

    meta_non_terminal(+meta_non_terminal_template_term)

    meta_non_terminal(+object_identifier::+meta_non_terminal_template_term)
    meta_non_terminal(+category_identifier::+meta_non_terminal_template_term)

    meta_non_terminal(+module_identifier:+meta_non_terminal_template_term)

## Examples

    :- meta_non_terminal(phrase(1, *)).
    phrase(X, T) --> call(X, T).

See also

meta_predicate/1, predicate_property/2