Editing Yacc (section)

== Impact ==
Yacc and similar programs (largely reimplementations) have been very popular. Yacc itself used to be available as the default parser generator on most Unix systems, though it has since been supplanted by more recent, largely compatible, programs such as [[Berkeley Yacc]], [[GNU bison|GNU Bison]], [[MKS Inc.|MKS]] Yacc, and Abraxas PCYACC. An updated version of the original AT&T Yacc is included as part of [[Sun Microsystems|Sun's]] [[OpenSolaris]] project. Each offers slight improvements and additional features over the original Yacc, but the concept and basic syntax have remained the same.<ref>[https://www.gnu.org/software/bison/manual/html_node/History.html#History Bison Manual: History]</ref>

Yacc was also one of several UNIX tools available for Charles River Data Systems' [[UNOS (operating system)|UNOS]] operating system under [[Bell Laboratories]] license.<ref>{{Cite book|year=1983|title=The Insider's Guide To The Universe|publisher=Charles River Data Systems, Inc.|url=https://www.1000bit.it/ad/bro/charles/CharlesRiverSystem-Universe.pdf|page=13}}</ref>

Among the languages that were first implemented with Yacc are [[AWK]], [[C++]],<ref name="oldcfront">{{cite web|last=Stroustrup|first=Bjarne |author-link=Bjarne Stroustrup |title=Cfront source code|url=http://www.softwarepreservation.org/projects/c_plus_plus/index.html#cfront}}</ref> [[eqn (software)|eqn]] and [[Pic language|Pic]].<ref>{{cite web|url=https://www.youtube.com/watch?v=vT_J6xc-Az0  |archive-url=https://ghostarchive.org/varchive/youtube/20211211/vT_J6xc-Az0| archive-date=2021-12-11 |url-status=live|title=UNIX Special: Profs Kernighan & Brailsford |work=Computerphile |date=September 30, 2015 }}{{cbignore}}</ref><ref name="cw" /> Yacc was also used on Unix to implement the [[Portable C Compiler]], as well as parsers for such programming languages as [[FORTRAN 77]], [[Ratfor]], [[APL (programming language)|APL]], [[bc (programming language)|bc]], [[m4 (computer language)|m4]], etc.<ref name="reader"/><ref>{{cite book|last1=Kernighan|first1=Brian W.|last2=Pike|first2=Rob|title=[[The Unix Programming Environment]]|year=1984|publisher=Prentice Hall|isbn=0-13-937681-X}}</ref>

Yacc has also been rewritten for other languages, including [[OCaml]],<ref>{{cite web |title=OCaml User's Manual: Chapter 12 Lexer and parser generators (ocamllex, ocamlyacc) |url=http://caml.inria.fr/pub/docs/manual-ocaml-4.00/manual026.html |access-date=25 Nov 2013}}</ref> [[Ratfor]], [[ML programming language|ML]], [[Ada (programming language)|Ada]], [[Pascal (programming language)|Pascal]], [[Java (programming language)|Java]], [[PHP]],  [[Python (programming language)|Python]], [[Ruby (programming language)|Ruby]], [[Go (programming language)|Go]],<ref>{{cite web |title=Yacc.go: A version of Yacc for the Go Programming Language |url=https://godoc.org/golang.org/x/tools/cmd/goyacc |access-date=15 July 2017}}</ref> [[Common Lisp]]<ref>{{cite web|title=CL-Yacc: A Common Lisp version of Yacc |url=http://www.pps.univ-paris-diderot.fr/~jch/software/cl-yacc/}}</ref> and [[Erlang (programming language)|Erlang]].<ref>{{cite web |title=yecc: An Erlang implementation of Yacc |url=http://erlang.org/doc/man/yecc.html}}</ref>

* [[Berkeley Yacc]]: The Berkeley implementation of Yacc quickly became more popular than AT&T Yacc itself because of its performance and lack of reuse restrictions.<ref>{{citation |title=flex & bison |author=John Levine |publisher=O'Reilly Media |date=August 2009 }}</ref>
* [[LALR parser]]: The underlying parsing algorithm in Yacc-generated parsers.
* [[GNU bison|Bison]]: The GNU version of Yacc.
* [[Lex programming tool|Lex]] (and [[Flex lexical analyser]]), a token parser commonly used in conjunction with Yacc (and Bison).
* [[Backus-Naur form|BNF]] is a [[metasyntax]] used to express [[context-free grammar]]s: that is a formal way to describe context-free languages.
* [[PLY (Python Lex-Yacc)]] is an alternative implementation of Lex and Yacc in Python.