Logtalk reference manual
Control construct: {}/1

{}/1

Description

{Goal}

Calls external Prolog code. Can be used to bypass the Logtalk compiler. The argument is called within the context of the pseudo-object user. It is also possible to use {Closure} as the first argument of call/2-N calls. In this case, Closure will be extended with the remaining arguments of the call/2-N call in order to construct a goal that will be called within the context of user.

This control construct may also be used in place of an object identifier when sending a message. In this case, the result of proving its argument is used as an object identifier in the message sending call.

Template and modes

{+callable}

Errors

Goal is a variable:
instantiation_error
Goal is neither a variable nor a callable term:
type_error(callable, Goal)

Examples

N1/D1 < N2/D2 :-
    {N1*D2 < N2*D1}.