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</style><table class="infobox vevent"><tbody><tr><th colspan="2" class="infobox-above" style="background-color:#e0e0e0;">FL</th></tr><tr><th scope="row" class="infobox-label"><a href="Programming_paradigm" title="Programming paradigm">Paradigm</a></th><td class="infobox-data"><a href="Function-level_programming" title="Function-level programming">Function-level</a>, <a href="Functional_programming" title="Functional programming">functional</a></td></tr><tr><th scope="row" class="infobox-label"><a href="Software_design" title="Software design">Designed by</a></th><td class="infobox-data"><a href="John_Backus" title="John Backus">John Backus</a><br>John Williams<br>Edward Wimmers</td></tr><tr><th scope="row" class="infobox-label">First appeared</th><td class="infobox-data">1989</td></tr><tr><th scope="row" class="infobox-label"><a href="Type_system" title="Type system">Typing discipline</a></th><td class="infobox-data"><a href="Dynamic_typing" class="mw-redirect" title="Dynamic typing">Dynamic</a></td></tr><tr><th colspan="2" class="infobox-header" style="background-color: #EEEEEE;">Influenced by</th></tr><tr><td colspan="2" class="infobox-full-data"><a href="FP_(programming_language)" title="FP (programming language)">FP</a></td></tr></tbody></table>
<p><b>FL</b> (short for "Function Level") is a <a href="Programming_language" title="Programming language">programming language</a> created at the <a href="IBM_Almaden_Research_Center" class="mw-redirect" title="IBM Almaden Research Center">IBM Almaden Research Center</a> by <a href="John_Backus" title="John Backus">John Backus</a>, John Williams, and Edward Wimmers in the 1980s and documented in a report from 1989.<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> FL was designed as a successor of Backus's earlier <a href="FP_(programming_language)" title="FP (programming language)">FP language</a>, providing specific support for what Backus termed <a href="Function-level_programming" title="Function-level programming">function-level programming</a>.
</p><p>FL is a dynamically typed strict <a href="Functional_programming" title="Functional programming">functional programming</a> language with throw and catch exception semantics much like in <a href="ML_(programming_language)" title="ML (programming language)">ML</a>. Each function has an implicit history argument which is used for doing things like strictly functional <a href="Input/output" title="Input/output">input/output</a> (I/O), but is also used for linking to <a href="C_(programming_language)" title="C (programming language)">C</a> code. For doing optimization, there exists a type-system which is an extension of <a href="Hindley%E2%80%93Milner_type_inference" class="mw-redirect" title="Hindley–Milner type inference">Hindley–Milner type inference</a>.
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<div class="mw-heading mw-heading2"><h2 id="Uses">Uses</h2></div>
<p><a href="PLaSM" title="PLaSM">PLaSM</a> is a "geometry-oriented extension of a subset of the FL language"<sup id="cite_ref-2" class="reference"><a href="#cite_note-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup> first described in 1992.
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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 id="CITEREFAikenWilliamsWimmers" class="citation web cs1">Aiken, Alexander; Williams, John H.; Wimmers, Edward L. <a rel="nofollow" class="external text" href="http://theory.stanford.edu/~aiken/publications/trs/FLProject.pdf">"The FL Project: Design of a Functional Language"</a> <span class="cs1-format">(PDF)</span>. <a href="Stanford_University" title="Stanford University">Stanford University</a>.</cite></span>
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<li id="cite_note-2"><span class="mw-cite-backlink"><b><a href="#cite_ref-2">^</a></b></span> <span class="reference-text"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="http://www.plasm.net/docs/tutorial/introduction_to_fl_and_plas.html">"Introduction to FL and PLaSM"</a>. <i>plasm.net</i>.</cite></span>
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<div class="mw-heading mw-heading2"><h2 id="External_links">External links</h2></div>
<ul><li><a rel="nofollow" class="external text" href="http://theory.stanford.edu/~aiken/publications/trs/RJ7100.pdf">FL Language Manual, Parts 1 and 2</a> (PDF)</li>
<li><a rel="nofollow" class="external text" href="http://www.plasm.net/docs/papers/fl_papers/">List of FL papers</a> at plasm.net</li>
<li><a rel="nofollow" class="external text" href="http://media.johnwiley.com.au/product_data/excerpt/29/04718994/0471899429.pdf">Introduction to FL and PLaSM</a> (PDF)</li></ul>
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