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Copyright @copyright{} 1995 SICS

Swedish Institute of Computer Science PO Box 1263 S-164 28 Kista, Sweden

Permission is granted to make and distribute verbatim copies of this manual provided the copyright notice and this permission notice are preserved on all copies.

Permission is granted to copy and distribute modified versions of this manual under the conditions for verbatim copying, provided that the entire resulting derived work is distributed under the terms of a permission notice identical to this one.

Permission is granted to copy and distribute translations of this manual into another language, under the above conditions for modified versions, except that this permission notice may be stated in a translation approved by SICS.


Prolog is a simple but powerful programming language developed at the University of Marseilles [Roussel 75], as a practical tool for programming in logic [Kowalski 74]. From a user's point of view the major attraction of the language is ease of programming. Clear, readable, concise programs can be written quickly with few errors.

For an introduction to programming in Prolog, readers are recommended to consult [Sterling & Shapiro 86]. However, for the benefit of those who do not have access to a copy of this book, and for those who have some prior knowledge of logic programming, a summary of the language is included. For a more general introduction to the field of Logic Programming see [Kowalski 79]. See section The Prolog Language.

This manual describes a Prolog system developed at the Swedish Institute of Computer Science. Parts of the system were developed by the project "Industrialization of SICStus Prolog" in collaboration with Ericsson Telecom AB, NobelTech Systems AB, Infologics AB and Televerket. The system consists of a WAM emulator written in C, a library and runtime system written in C and Prolog and an interpreter and a compiler written in Prolog. The Prolog engine is a Warren Abstract Machine (WAM) emulator [Warren 83]. Two modes of compilation are available: in-core i.e. incremental, and file-to-file. Implementation details can be found in [Carlsson 90] and in several technical reports available from SICS.

When compiled, a predicate will run about 8 times faster and use memory more economically. However, it is recommended that the new user should gain experience with the interpreter before attempting to use the compiler. The interpreter facilitates the development and testing of Prolog programs as it provides powerful debugging facilities. It is only worthwhile compiling programs which are well-tested and are to be used extensively.

SICStus Prolog follows the mainstream Prolog tradition in terms of syntax and built-in predicates, and is largely compatible with DECsystem-10 and Quintus Prologs.

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