Editing Lispkit Lisp

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{{Notability|date=June 2018}}
{{Primary sources|date=June 2018}}
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{{Infobox programming language
| name = Lispkit Lisp
| screenshot = <!-- Filename -->
| screenshot caption = 
| sampleCode = 
| paradigm =[[Purely functional programming|pure functional]]
| family = [[Lisp (programming language)|Lisp]]
| designer = Peter Henderson
| developer = <!-- or: | developers = -->
| released = {{Start date and age|1980}}
| latest release version = 
| latest release date = {{Start date and age|1983}}
| typing = 
| memory management =
| scope = [[Scope (computer science)|lexical]]
| programming language = [[ALGOL]]
| discontinued = Yes
| platform = 
| operating system = 
| license = 
| file ext = 
| file format = <!-- or: | file formats = -->
| website = <!-- {{URL|www.example.com}} -->
| implementations = 
| dialects = 
| influenced by = [[ALGOL]], [[Lisp (programming language)|Lisp]]
| influenced = 
}}
'''Lispkit Lisp''' is a [[Lexical scoping|lexically scoped]], [[Purely functional programming|purely functional]] subset of [[Lisp (programming language)|Lisp]] ('''Pure Lisp''') developed as a testbed for [[functional programming]] concepts. It was first used for early experimentation with [[lazy evaluation]]. An implementation based on a ''stack, environment, control, dump'' [[virtual machine]] and [[abstract machine]] ([[SECD machine]]) written in an [[ALGOL]] variant was published by the developer Peter Henderson in 1980.<ref name="henderson">{{cite book |last1=Henderson |first1=Peter |year=1980 |title=Functional Programming: Application and Implementation |publisher=Prentice Hall |isbn=0-13-331579-7}}</ref> The [[compiler]] and [[virtual machine]] are highly [[porting|portable]] and as a result have been implemented on many machines.<ref>
{{cite web |last1=McJones |first1=Paul |date=12 May 2014 |title=Original OUCL PRG LispKit |website=[[Computer History Museum]]: Software Preservation Group |publisher=University of Oxford |publication-place=Mountain View, California |url=https://www.softwarepreservation.org/projects/LISP/lispkit/LispKit.tar.gz/view |via=Plone Foundation}}</ref><ref>
{{cite web |last1=McJones |first1=Paul |date=12 May 2014 |title=Aaron Gray's port of LispKit to GNU Pascal |website=[[Computer History Museum]]: Software Preservation Group |publisher=Cybercomms.org |publication-place=Mountain View, California |url=https://www.softwarepreservation.org/projects/LISP/lispkit/LispKit-GNU_Pascal.tar.gz/view |via=Plone Foundation}}</ref>

== Base language ==
The base language provides the following functions only but extensions are discussed in Henderson's book<ref name="henderson"/> for the explicit support of lazy evaluation and [[nondeterministic programming]].
:<code>atom</code> – given an expression returns True if its value is atomic; False if not
:<code>add</code> – given two expressions returns the sum of their numeric values
:<code>car</code> – given an expression whose value is a pair, returns the pair's first value
:<code>cdr</code> – given an expression whose value is a pair, returns the pair's second value
:<code>cons</code> – given two expressions returns a value pair consisting of their values
:<code>div</code> – given two expressions returns the quotient of their numeric values
:<code>eq</code> – given two expressions returns True if their values are equal; False if not
:<code>if</code> – given three expressions returns the value of the second if the value of the first is True, otherwise returns the value of the third
:<code>lambda</code> – given an argument list and an expression, returns them as a function
:<code>let</code> – given an expression with declarations (as named expressions visible in the expression) returns its value
:<code>letrec</code> – like let, except the declared names are also visible in the declarations themselves
:<code>leq</code> – given two expressions, returns True if the value of the first is numerically less than or equal to the value of the second; False if not
:<code>mod</code> (or <code>rem</code>) – given two expressions, returns the modulus (also known as the remainder) of their numeric values
:<code>mul</code> – given two expressions, returns the product of their numeric values
:<code>quote</code> – given an expression, returns that expression as a value
:<code>sub</code> – given two expressions, returns the difference of their numeric values

The functions, <code>lambda</code>, <code>let</code>, and <code>letrec</code>, are similar but have subtle differences in the way that they treat named variables which make them useful in different ways: <code>lambda</code> defines and returns a function, <code>let</code> binds expressions to variable names, and <code>letrec</code> is essentially similar to <code>let</code> except it allows defining of [[Recursion (computer science)|recursive]] functions and values, e.g., [[Series (mathematics)|infinite series]].

== References ==
{{Reflist}}

== Further reading ==
*{{cite book |last1=Henderson |first1=Peter |last2=Jones |first2=Geraint A. |last3=Jones |first3=Simon B. |date=1 December 1983 |title=The LispKit Manual |publisher=[[University of Oxford]] Computing Laboratory |isbn=978-0902928183}}
*{{cite book |last1=Henderson |first1=Peter |last2=Jones |first2=Geraint A. |last3=Jones |first3=Simon B. |date=1 December 1983 |url=http://www.cs.ox.ac.uk/files/3299/PRG32%20vol%201.pdf |title=The LispKit Manual: Volume 1 |publication-place=Oxford, England |publisher=[[University of Oxford]]: Computing Laboratory: Programming Research Group}}
*{{cite book |last1=Henderson |first1=Peter |last2=Jones |first2=Geraint A. |last3=Jones |first3=Simon B. |date=1 December 1983 |url=http://www.cs.ox.ac.uk/files/3300/PRG32%20vol%202.pdf |title=The LispKit Manual: Volume 2 |publication-place=Oxford, England |publisher=[[University of Oxford]]: Computing Laboratory: Programming Research Group}}

== External links ==
* [https://github.com/hanshuebner/secd/tree/master/lispkit/LKIT-2 Archive of old LispKit Lisp code and files, plus C implementation of SECD machine]
* [http://perun.pmf.uns.ac.rs/radovanovic/publications/2002-prim-lisp.pdf Paper about a LispKit Lisp implementation in Java], and [https://perun.pmf.uns.ac.rs/radovanovic/downloads.htm the implementation]

{{Lisp programming language}}

[[Category:Lisp programming language family]]