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<span id="openzim-page-title" class="mw-page-title-main"><span class="mw-page-title-main">SLIP (programming language)</span></span>
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</style><div role="note" class="hatnote navigation-not-searchable">Not to be confused with <a href="Serial_Line_Internet_Protocol" title="Serial Line Internet Protocol">Serial Line Internet Protocol</a>.</div>
<p><b>SLIP</b> is a list processing <a href="Computer_programming_language" class="mw-redirect" title="Computer programming language">computer programming language</a>, invented by <a href="Joseph_Weizenbaum" title="Joseph Weizenbaum">Joseph Weizenbaum</a> in the 1960s. The name <i>SLIP</i> stands for <b>S</b>ymmetric <b>LI</b>st <b>P</b>rocessor. It was first implemented as an extension to the <a href="Fortran" title="Fortran">Fortran</a> programming language, and later embedded into <a href="MAD_programming_language" class="mw-redirect" title="MAD programming language">MAD</a> and <a href="ALGOL" title="ALGOL">ALGOL</a>.<sup id="cite_ref-1" class="reference"><a href="#cite_note-1"><span class="cite-bracket">[</span>1<span class="cite-bracket">]</span></a></sup> The best known program written in the language is <a href="ELIZA" title="ELIZA">ELIZA</a>, an early <a href="Natural_language_processing" title="Natural language processing">natural language processing</a> <a href="Computer_program" title="Computer program">computer program</a> created by Weizenbaum<sup id="cite_ref-turing_2-0" class="reference"><a href="#cite_note-turing-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup> at the <a href="MIT_Computer_Science_and_Artificial_Intelligence_Laboratory" title="MIT Computer Science and Artificial Intelligence Laboratory">MIT Artificial Intelligence Laboratory</a>.<sup id="cite_ref-:0_3-0" class="reference"><a href="#cite_note-:0-3"><span class="cite-bracket">[</span>3<span class="cite-bracket">]</span></a></sup>
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<div class="mw-heading mw-heading2"><h2 id="General_overview">General overview</h2></div>
<p>In a nutshell, SLIP consisted of a set of FORTRAN "accessor" functions which operated on <a href="Doubly_linked_list" title="Doubly linked list">circular doubly linked lists</a> with fixed-size data fields. The "accessor" functions had direct and indirect addressing variants.
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<div class="mw-heading mw-heading2"><h2 id="List_representation">List representation</h2></div>
<p>The list representation had four types of cell: a <i>reader</i>, a <i>header</i>, a <i>sublist indicator</i>, and a <i>payload</i> cell. The header included a reference count field for <a href="Garbage_collection_(computer_science)" title="Garbage collection (computer science)">garbage collection</a> purposes. The sublist indicator allowed it to be able to represent nested lists, such as (A, B, C, (1, 2, 3), D, E, F) where (1, 2, 3) is a sublist indicated by a cell in the '*' position in the list (A, B, C, *, D, E, F). The reader was essentially a state history stack—a good example of a <a href="Memento_pattern" title="Memento pattern">memento pattern</a>—where each cell pointed to the header of the list being read, the current position within the list being read, and the level or depth of the history stack.
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<div class="mw-heading mw-heading2"><h2 id="References">References</h2></div>
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<li id="cite_note-1"><span class="mw-cite-backlink"><b><a href="#cite_ref-1">^</a></b></span> <span class="reference-text"><style data-mw-deduplicate="TemplateStyles:r1238218222">
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</style><cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://web.archive.org/web/20220117222654/http://www.heuse.com/s.htm">"Computer Programming Languages – S"</a>. Archived from <a rel="nofollow" class="external text" href="http://www.heuse.com/s.htm">the original</a> on 2022-01-17<span class="reference-accessdate">. Retrieved <span class="nowrap">2006-03-20</span></span>.</cite></span>
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<li id="cite_note-turing-2"><span class="mw-cite-backlink"><b><a href="#cite_ref-turing_2-0">^</a></b></span> <span class="reference-text"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="http://news.harvard.edu/gazette/story/2012/09/alan-turing-at-100/">"Alan Turing at 100"</a>. <i>Harvard Gazette</i>. 13 September 2012<span class="reference-accessdate">. Retrieved <span class="nowrap">2016-02-22</span></span>.</cite></span>
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<li id="cite_note-:0-3"><span class="mw-cite-backlink"><b><a href="#cite_ref-:0_3-0">^</a></b></span> <span class="reference-text"><cite id="CITEREFWeizenbaum1976" class="citation book cs1">Weizenbaum, Joseph (1976). <a rel="nofollow" class="external text" href="https://archive.org/details/computerpowerhum0000weiz/page/2"><i>Computer Power and Human Reason: From Judgment to Calculation</i></a>. New York: W.H. Freeman and Company. pp. <a rel="nofollow" class="external text" href="https://archive.org/details/computerpowerhum0000weiz/page/2">2, 3, 6, 182, 189</a>. <a href="ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <bdi>0-7167-0464-1</bdi>.</cite></span>
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<ul><li><i><a rel="nofollow" class="external text" href="https://dl.acm.org/doi/10.1145/367593.367617">Symmetric List Processor</a></i>, Joseph Weizenbaum, CACM 6:524-544(1963). Sammet 1969, p. 387.</li>
<li><i><a href="Computer_Power_and_Human_Reason" title="Computer Power and Human Reason">Computer Power and Human Reason: From Judgment To Calculation</a></i>, Joseph Weizenbaum, San Francisco: W. H. Freeman, 1976 <a href="ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <bdi>0-7167-0463-3</bdi></li></ul>
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