yap-6.3/docs/md/core.md

@defgroup builtins Core Built-ins

[TOC]


This chapter describes the core built-in predicates  that control the execution of
Prolog programs, provide fundamental functionality such as termm manipulation or arithmetic, and support interaction with external
resources.

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Many of the predicates described here have been standardised by the International Standard Organization.
 The corresponding standartised subset of Prolog also known as ISO-Prolog.    

In the description of the arguments of predicates the following
notation will be used:

+ a preceding plus sign will denote an argument as an "input
	argument" - the argument is read, not written, and it cannot
	be a free variable at the time of the call;

+ a preceding minus sign will denote an "output argument";

+ an argument with no preceding symbol can be used in both ways.




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