Editing Prolog (section)

=== Types ===
Prolog is an untyped language. Attempts to introduce and extend Prolog with types began in the 1980s,<ref>{{Cite journal |doi=10.1016/0004-3702(84)90017-1 |last1=Mycroft |first1=A. |last2=O'Keefe |first2=R. A. |title=A polymorphic type system for prolog |journal=[[Artificial Intelligence (journal)|Artificial Intelligence]] |volume=23 |issue=3 |page=295 |year=1984}}</ref><ref>{{cite book |author=Pfenning, Frank |title=Types in logic programming |publisher=MIT Press |location=Cambridge, Massachusetts |year=1992 |isbn=978-0-262-16131-2}}</ref> and continue {{as of|2008|lc=y}}.<ref>{{Cite book |last1=Schrijvers |first1=Tom |last2=Santos Costa |first2=Vitor |last3=Wielemaker |first3=Jan |last4=Demoen |first4=Bart |year=2008 |chapter=Towards Typed Prolog |editor1=María García de la Banda |editor1-link=María García de la Banda|editor2=Enrico Pontelli |title=Logic programming: 24th international conference, ICLP 2008, Udine, Italy, December 9-13, 2008: proceedings |series=Lecture Notes in Computer Science |volume=5366 |pages=693–697 |doi=10.1007/978-3-540-89982-2_59 |isbn=978-3-540-89982-2 |chapter-url=https://lirias.kuleuven.be/handle/123456789/197561}}</ref> Type information is useful not only for [[type safety]] but also for reasoning about Prolog programs.<ref name="cite doi|10.1007/BF01213601">{{Cite journal |doi=10.1007/BF01213601 |last1=Apt |first1=K. R. |last2=Marchiori |first2=E. |title=Reasoning about Prolog programs: From modes through types to assertions |journal=Formal Aspects of Computing |volume=6 |issue=S1 |page=743 |year=1994 |url=http://www.cwi.nl/~apt/am.ps |citeseerx=10.1.1.57.395 |s2cid=12235465}}</ref>