built-in method

call//1-N

Description

call(Closure)
call(Closure, Arg1, ...)
call(Object::Closure, Arg1, ...)
call(::Closure, Arg1, ...)
call(^^Closure, Arg1, ...)
...

This non-terminal takes a closure and is processed by appending the two implicit grammar rule arguments to the arguments of the closure. This built-in non-terminal is interpreted as a private non-terminal and thus cannot be used as a message to an object.

Using this non-terminal is recommended when calling a predicate whose last two arguments are the two implicit grammar rule arguments to avoid hard-coding assumptions about how grammar rules are compiled into clauses. Note that the compiler ensures zero overhead when using this non-terminal with a bound argument at compile time. To call a predicate with a different argument order, use a lambda expression or define a predicate alias. For example:

square -->
    call([Number, Double]>>(Double is Number*Number)).

When using a backend Prolog compiler supporting a module system, calls in the format call(Module:Closure) may also be used.

Meta-non-terminal template

call(0)
call(1, *)
call(2, *, *)
...

Modes and number of proofs

call(+callable) - zero_or_more
call(+callable, ?term) - zero_or_more
call(+callable, ?term, ?term) - zero_or_more
...

Errors

Closure is a variable:

instantiation_error

Closure is neither a variable nor a callable term:

type_error(callable, Closure)

Examples

Calls a goal, constructed by appending the two implicit grammar rule arguments to the closure, in in the context of the object or category containing the call:

call(Closure)

To make a super call, constructed by appending the two implicit grammar rule arguments to the closure:

call(^^Closure)

To send a goal, constructed by appending the two implicit grammar rule arguments to the closure, as a message to self:

call(::Closure)

To send a goal, constructed by appending the two implicit grammar rule arguments to the closure, as a message to an explicit object:

call(Object::Closure)

See also

eos//0, phrase//1, phrase/2, phrase/3