Editing Association list (section)

==Applications and software libraries==
In the early development of Lisp, association lists were used to resolve references to [[Free variables and bound variables|free variables]] in procedures.<ref name="mccarthy_lisp_1.5">{{cite book | url = https://archive.org/details/lisp15programmer00john | title = LISP 1.5 Programmer's Manual | publisher = [[MIT Press]] | first1 = John | last1 = McCarthy | first2 = Paul W. | last2 = Abrahams | first3 = Daniel J. | last3 = Edwards | first4 = Timothy P. | last4 = Hart | first5 = Michael I. | last5 = Levin | isbn = 0-262-13011-4 | year = 1985 | url-access = registration }} See in particular p.&nbsp;12 for functions that search an association list and use it to substitute symbols in another expression, and p.&nbsp;103 for the application of association lists in maintaining variable bindings.</ref><ref>{{cite book|title=What Computing Is All About|series=Monographs in Computer Science|first=Jan L. A.|last=van de Snepscheut|publisher=Springer|year=1993|isbn=9781461227106|page=201|url=https://books.google.com/books?id=VXPrBwAAQBAJ&pg=PA201}}</ref> In this application, it is convenient to augment association lists with an additional operation, that reverses the addition of a key–value pair without scanning the list for other copies of the same key. In this way, the association list can function as a [[Stack (abstract data type)|stack]], allowing [[local variables]] to temporarily [[Variable shadowing|shadow]] other variables with the same names, without destroying the values of those other variables.<ref>{{cite book|title=Programming Language Pragmatics|first=Michael Lee|last=Scott|publisher=Morgan Kaufmann|year=2000|isbn=9781558604421|page=137|contribution-url=https://books.google.com/books?id=To3xpkvkPvMC&pg=PA137|contribution=3.3.4 Association Lists and Central Reference Tables}}</ref>

Many programming languages, including
Lisp,<ref name="mccarthy_lisp_1.5"/>
[[Scheme (programming language)|Scheme]],<ref>{{cite book|title=Programming and Meta-Programming in Scheme|series=Undergraduate Texts in Computer Science|first=Jon|last=Pearce|publisher=Springer|year=2012|isbn=9781461216827|page=214|url=https://books.google.com/books?id=uDzaBwAAQBAJ&pg=PA214}}</ref>
[[OCaml]],<ref>{{cite book|title=Real World OCaml: Functional Programming for the Masses|first1=Yaron|last1=Minsky|first2=Anil|last2=Madhavapeddy|first3=Jason|last3=Hickey|publisher=O'Reilly Media|year=2013|isbn=9781449324766|page=253|url=https://books.google.com/books?id=nabtAQAAQBAJ&pg=PA253}}</ref> and
[[Haskell (programming language)|Haskell]]<ref>{{cite book|title=Real World Haskell: Code You Can Believe In|first1=Bryan|last1=O'Sullivan|first2=John|last2=Goerzen|first3=Donald Bruce|last3=Stewart|publisher=O'Reilly Media|year=2008|isbn=9780596554309|page=299|url=https://books.google.com/books?id=nh0okI1a1sQC&pg=PA299}}</ref> have functions for handling association lists in their [[standard library|standard libraries]].