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The Prolog Library

The Prolog library comprises a number of packages which are thought to be useful in a number of applications. Note that the predicates in the Prolog library are not built-in predicates. One has to explicitly load each package to get access to its predicates. The following packages are provided:

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provides an implementation of extendable arrays with logarithmic access time.

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uses AVL trees to implement "association lists", i.e. extendable finite mappings from terms to terms.

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provides a means of associating with variables arbitrary attributes, i.e. named properties that can be used as storage locations as well as hooks into Prolog's unification.

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implements binary heaps, the main application of which are priority queues.

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provides basic operations on lists.

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provides a number of operations on terms.

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defines operations on sets represented as lists with the elements ordered in Prolog standard order.

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defines operations on queues (FIFO stores of information).

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provides a random number generator.

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provides access to operating system services.

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uses binary trees to represent non-extendable arrays with logarithmic access time. The functionality is very similar to that of library(arrays), but library(trees) is slightly more efficient if the array does not need to be extendable.

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provides an implementation of directed and undirected graphs with unlabelled edges.

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provides an implementation of directed and undirected graphs where each edge has an integral weight.

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provides an interface to system calls for manipulating sockets.

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provides an implementation of the Linda concept for process communication.

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provides storage and retrieval of terms on disk files with user-defined multiple indexing.

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provides constraint solving over Booleans.

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provides constraint solving over Q (Rationals) or R (Reals).

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provides the combination of the logic programming and the object-oriented programming paradigms.

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is a specification tool that is based on Generalized Horn Clause Language, a generalization of Prolog.

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An interface to the Tcl/Tk language and toolkit.

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is a profiling tool for Prolog programs with a graphical interface based on tcltk.

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defines IO predicates that read from, or write to, a list of character codes.

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is a utility program for generating glue code for the Foreign Language Interface when building Runtime Systems or statically linked Development Systems.

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provides a way of running goals with an execution time limit.

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provides a cross reference producer for debugging and program analysis.

To load a library package Package, you will normally enter a query

| ?- use_module(library(Package)).

Library packages may be compiled and consulted as well as loaded.

An alternative way of loading from the library is using the built-in predicate require/1 (see section Reading-in Programs). The index file `INDEX.pl' needed by require/1 can be created by the make_index program. This program is loaded as:

| ?- use_module(library(mkindex)).

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Creates a file `INDEX.pl' in LibraryDirectory. All `*.pl' files in the directory and all its subdirectories are scanned for module/2 declarations. From these declarations, the exported predicates are entered into the index.

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