Hope (programming language): Difference between revisions

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{{Infobox programming language

'''Hope''' is a small [[functional programming language]] developed in the 1970s at the [[University of Edinburgh]].<ref name="BMS">[[Rod Burstall|Burstall R.M]], MacQueen D.B, Sannella D.T. (1980) ''Hope: An Experimental Applicative Language''. Conference Record of the 1980 LISP Conference, Stanford University, pp. 136-143.</ref><ref>

| name = Hope

{{cite book

| logo = <!-- Filename -->

| title = Functional Programming with Hope

| logo caption =

| series = Ellis Horwood Series in Computers and Their Applications

| screenshot = <!-- Filename -->

| last = Bailey

| screenshot caption =

| first = Roger

| sampleCode =

| publisher = Ellis Horwood Ltd

| paradigm = [[Functional programming|functional]]

| date = 1 April 1990

| issuefamily = 8

}}</ref>

| designers = [[Rod Burstall]]<br>D. B. MacQueen<br>[[Don Sannella]]

It predates [[Miranda (programming language)|Miranda]] and [[Haskell (programming language)|Haskell]] and is contemporaneous with [[ML (programming language)|ML]], also developed at the University. Hope was derived from [[NPL (programming language)|NPL]],<ref name="design"/> a simple functional language developed by [[Rod Burstall]] and John Darlington in their work on program transformation.<ref>R.M. Burstall and J. Darlington. A transformation system for developing recursive programs. Journal of the Association for Computing Machinery, 24(1):44–67 (1977)</ref> NPL and Hope are notable for being the first languages with call-by-pattern evaluation and [[algebraic data types]].<ref>{{Cite book|last=Hudak|first=Paul|last2=Hughes|first2=John|last3=Peyton Jones|first3=Simon|last4=Wadler|first4=Philip|date=2007-06-09|title=A history of Haskell: being lazy with class|publisher=ACM|pages=12–1|doi=10.1145/1238844.1238856|isbn=9781595937667}}</ref>

| developer =[[University of Edinburgh]]

| released = {{Start date and age|1980}}

| latest release version =

| latest release date = <!-- {{Start date and age|199y|mm|dd|df=yes}} -->

| typing =

| memory management =

| scope =

| programming language =

| discontinued = Yes

| platform =

| operating system =

| license =

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| file format = <!-- or: | file formats = -->

| website = <!-- {{URL|www.example.com}} -->

| implementations =

| dialects = Hope+

| influenced by = [[NPL (programming language)|NPL]]

| influenced =

}}

'''Hope''' is a small[[programming language]] based on [[functional programming language]] developed in the 1970s at the [[University of Edinburgh]].<ref name="BMS">[[Rod{{cite book Burstall|last1=Burstall |first1=R. M]],. |author1-link=Rod Burstall |last2=MacQueen |first2=D. B,. |last3=Sannella |first3=D. T. (|date=1980) ''|chapter=Hope: An Experimental Applicative Language'' |title=Proc. Conference Record of the 1980 LISP Conference|place=Stanford University, Stanford, UniversityCalifornia, pp.United 136-143States |page=136–143 |url=https://homepages.inf.ed.ac.uk/dts/pub/hope.pdf}}</ref><ref>

{{cite book |last1=Bailey |first1=Roger |date=1 April 1990 |title=Functional Programming with Hope |series=Ellis Horwood Series in Computers and Their Applications |publisher=Ellis Horwood Ltd}}</ref>

It predates [[Miranda (programming language)|Miranda]] and [[Haskell (programming language)|Haskell]] and is contemporaneous with [[ML (programming language)|ML]], also developed at the University. Hope was derived from [[NPL (programming language)|NPL]],<ref name="design"/> a simple functional language developed by [[Rod Burstall]] and [[John Darlington]] in their work on program transformation.<ref>{{cite journal |last1=Burstall |first1=R. M. |author1-link=Rod Burstall and|last2=Darlington |first2=J. |author2-link=John Darlington. |date=1977 |title=A transformation system for developing recursive programs. |journal=Journal of the Association for Computing Machinery, |volume=24( |issue=1):44–67 (1977)|pages=44–67}}</ref> NPL and Hope are notable for being the first languages with call-by-pattern evaluation and [[algebraic data typestype]]s.<ref>{{Cite book |lastlast1=Hudak |firstfirst1=Paul |author1-link=Paul Hudak |last2=Hughes |first2=John |author2-link=John Hughes (computer scientist) |last3=Peyton Jones |first3=Simon |author3-link=Simon Peyton Jones |last4=Wadler |first4=Philip |author4-link=Philip Wadler |date=2007-06-09 |title=A history of Haskell: being lazy with class |publisher=ACM |pages=12–1 |doi=10.1145/1238844.1238856 |isbn=9781595937667 |s2cid=52847907}}</ref>

Hope was named for [[Sir Thomas Hope, 8th Baronet|Sir Thomas Hope]] (c. 1681–1771), a Scottish agricultural[[agriculture]] reformer, after whom ''Hope Park Square'' in [[Edinburgh]], the ___location of the Department[[artificial of Artificialintelligence]] Intelligencedepartment at the time of the development of Hope, was also named.

The first implementation of Hope used [[strict evaluation]], but there have since been [[lazy evaluation]] versions and strict versions with lazy constructors. A successor language Hope+, developed jointly between [[Imperial College]] and [[International Computers Limited]], added annotations to dictate either strict or lazy evaluation.<ref name=annotations>{{cite book |last1=Kewley |first1=John |last2=Glynn |first2=Kevin |date=1989 |chapter=Evaluation Annotations for Hope+ |editor1-last=Davis |editor1-first=Kei |editor2-last=Hughes |editor2-first=R. J. M. |title=Functional Programming: Proceedings of the 1989 Glasgow Workshop, Workshops in Computing |pages=329–337 |place=London, United Kingdom |publication-date=1990 |publisher=[[Springer-Verlag]]}}</ref>

Hope was named for [[Sir Thomas Hope, 8th Baronet|Sir Thomas Hope]] (c. 1681–1771), a Scottish agricultural reformer, after whom ''Hope Park Square'' in Edinburgh, the ___location of the Department of Artificial Intelligence at the time of the development of Hope, was also named.

==Language details==

A [[factorial]] program in Hope is:

dec fact : num -> num;

--- fact 0 <= 1;

--- fact n <= n*fact(n-1);

Changing the order of the clauses does not change the meaning of the program, because Hope's pattern matching always favors more specific patterns over less specific ones. Explicit type[[Declaration (computer programming)|declarations]] of [[data type]]s in Hope are required; there is no option[[type to use a type-inference]] algorithm in Hope.

Hope provides two built-in [[data structuresstructure]]s: tuples[[tuple]]s and [[List (abstract data type)|lists]].<ref name=byte/>

==Implementations==

TheRoger firstBailey's implementationHope oftutorial Hopein wasthe August 1985 issue of ''[[strictByte evaluation(magazine)|strictByte]],'' butreferences since that one there have beenan [[lazyInterpreter evaluation(computing)|lazyinterpreter]] versionsfor and[[IBM strictPC versionsDOS]] with2.0.<ref lazyname=byte/> constructors.[[BT Group|British Telecom]] embarked on a project with [[Imperial College London|Imperial College]] to implement a strict version of Hope. The first release was coded by Thanos Vassilakis in 1986. Further releases were coded by Mark Tasng of British Telecom. A successor language Hope+ (decevloped jointly between [[Imperial College]] and [[ICL]] added annotations to dictate either strict or lazy evaluation.

Roger Bailey's Hope tutorial in the August 1985 issue of ''[[Byte (magazine)|BYTE]]'' references an interpreter for [[IBM PC DOS]] 2.0.<ref name=byte/>

==References==

{{Reflist|refs=

<ref name="design">{{cite conference |last1=Burstall |first1=R. M. |author1-link=Rod Burstall. |date=1977 |title=Design considerations for a functional programming language. Invited(invited paper,) Proc.|conference=Proceedings Infotech State of the Art Conf.Conference “The"The Software Revolution”,Revolution" |place=Copenhagen, |pages=45–57 (1977)}}</ref>

<ref name=byte>{{cite magazine |last1=Bailey |first1=Roger |date=August 1985 |url=https://archive.org/stream/BYTE_Vol_10-08_1985-08_The_Amiga#page/n241/mode/2up |title=A Hope Tutorial |magazine=[[Byte (magazine)|Byte]] |volume=10 |issue=8 |page=235–258 |access-date=13 January 2025}}</ref>

<ref name=byte>

{{cite magazine

| title = A Hope Tutorial

| last = Bailey

| first = Roger

| magazine = [[Byte magazine|BYTE]]

| volume = 10

| issue = 8

| date = August 1985

| url = https://archive.org/stream/BYTE_Vol_10-08_1985-08_The_Amiga#page/n241/mode/2up

| accessdate = 1 April 2015

}}</ref>

}}

==External links==

*[https://web.archive.org/web/20130801064002/http://www.hopemachine.co.uk/ Hope Interpreter for Windows]

*[http://cgibin.erols.com/ziring/cgi-bin/cep/cep.pl?_key=Hope Entry for Hope in the online Dictionary of Programming Languages]

{{Authority control}}

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[[Category:Functional languages]]

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[[Category:History of computing in the United Kingdom]]

[[Category:Statically typed programming languages]]

[[Category:University of Edinburgh]]

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