YAP (Prolog)
{{Short description|Programming language implementation}}
{{No footnotes|date=May 2012}}
{{Infobox Software
| name = YAP Prolog
| logo =
| screenshot =
| caption =
| developer =
| latest_release_version = 6.3.3
| latest_release_date = {{Start date and age|2013|01|21|df=yes}}
| latest preview version = 7.1
| latest preview date = {{Start date and age|2016|01|09|df=yes}}
| operating_system = Linux, Windows, Solaris, Mac OS X
| platform = Programming language
| license = Perl Artistic License 2.0
| website = {{URL|www.dcc.fc.up.pt/~vsc/yap/}}
| repo = {{URL|github.com/vscosta/yap}}
}}
YAP is an open-source, high-performance implementation of the Prolog programming language developed at LIACC/Universidade do Porto and at COPPE Sistemas/UFRJ. Its Prolog engine is based in the WAM (Warren Abstract Machine), with several optimizations for better performance. YAP follows the Edinburgh tradition, and is largely compatible with the ISO-Prolog standard and with Quintus Prolog and SICStus Prolog. YAP has been developed since 1985. The original version was written in assembly, C and Prolog, and achieved high performance on m68k-based machines.