Scheme 48

<h2 id="implementation">Implementation</h2>
<p class="note">"PreScheme" redirects here. For the use of this term in mathematics, see <a href="/facts/Scheme_(mathematics)/c7uSqGqL">Scheme (mathematics) § Definition</a>.</p>
<p>Scheme 48 uses a <a href="/facts/Virtual_machine/BLevU3sx">virtual machine</a> to interpret the <a href="/facts/Bytecode/EPkMFR7M">bytecode</a>, which is written in a restricted dialect of Scheme called PreScheme, which can be translated to C and compiled to a native binary. PreScheme, or Pre-Scheme, is a statically-typed dialect of Scheme with the efficiency and low-level machine access of C while retaining many of the desirable features of Scheme.
</p>
<blockquote><p>Pre-scheme was quite interesting. Kelsey published a paper on it, as well, I believe. It was Scheme in the sense that you could load it into a Scheme system and run the code. But it was restrictive – it required you to write in a fashion that allowed complete Hindley-Milner static type inference, and all higher-order procedures were beta-substituted away at compile time, meaning you could *straightforwardly* translate a prescheme program into "natural" C code with C-level effiency [<i><a href="/facts/Sic/qB9MUUWF">sic</a></i>]. That is, you could view prescheme as a really pleasant alternative to C for low-level code. And you could debug your prescheme programs in the interactive Scheme development environment of your choice, before flipping a switch and translating to C code, because prescheme was just a restricted Scheme. The Scheme 48 byte-code interpreter was written in prescheme. Prescheme sort of died – beyond the academic paper he wrote, Kelsey never quite had the time to document it and turn it into a standalone tool that other people could use (Ian Horswill's group at Northwestern is an exception to that claim – they have used prescheme</p>— Olin Shivers, "Olin Shivers: History of T"<a class="footnote-ref" id="fnref:8" href="#fn:8"><sup>8</sup></a></blockquote>

<h2 id="external-links">External links</h2>
<ul><li><a href="http://s48.org">Official website</a></li></ul>

<h2 id="references">References</h2>

<ol>
<li id="fn:1"><p>Kelsey, Richard; Rees, Jonathan. "Scheme 48". S48.org. Retrieved 2018-12-05. <a href="http://s48.org/" target="_blank">http://s48.org/</a> <a href="#fnref:1" class="footnote-back-ref">↩</a></p></li>
<li id="fn:2"><p>Kelsey, Richard; Rees, Jonathan; Sperber, Mike (10 January 2008). "The Incomplete Scheme 48 Reference Manual for release 1.8: Mixing Scheme 48 and C". S48.org. Retrieved 2018-12-05., Chapter 8 in manual for version 1.8. <a href="http://s48.org/1.8/manual/manual-Z-H-9.html#node_sec_8.3" target="_blank">http://s48.org/1.8/manual/manual-Z-H-9.html#node_sec_8.3</a> <a href="#fnref:2" class="footnote-back-ref">↩</a></p></li>
<li id="fn:3"><p>Kelsey, Richard; Rees, Jonathan; Sperber, Mike (10 January 2008). "The Incomplete Scheme 48 Reference Manual for release 1.8: Regular Expressions". S48.org. Retrieved 2018-12-05., Chapter 5 in manual for version 1.8. <a href="http://s48.org/1.8/manual/manual-Z-H-6.html#node_sec_5.20" target="_blank">http://s48.org/1.8/manual/manual-Z-H-6.html#node_sec_5.20</a> <a href="#fnref:3" class="footnote-back-ref">↩</a></p></li>
<li id="fn:4"><p>Kelsey, Richard; Rees, Jonathan; Sperber, Mike (10 January 2008). "The Incomplete Scheme 48 Reference Manual for release 1.8: Access to POSIX". S48.org. Retrieved 2018-12-05., Chapter 9 in manual for version 1.8. <a href="http://s48.org/1.8/manual/manual-Z-H-10.html#node_chap_9" target="_blank">http://s48.org/1.8/manual/manual-Z-H-10.html#node_chap_9</a> <a href="#fnref:4" class="footnote-back-ref">↩</a></p></li>
<li id="fn:5"><p>Kelsey, Richard; Rees, Jonathan. "Scheme 48". S48.org. Retrieved 2018-12-05. <a href="http://s48.org/" target="_blank">http://s48.org/</a> <a href="#fnref:5" class="footnote-back-ref">↩</a></p></li>
<li id="fn:6"><p>Final shift for call/cc: direct implementation of shift and reset <a href="http://dl.acm.org/citation.cfm?id=581504" target="_blank">http://dl.acm.org/citation.cfm?id=581504</a> <a href="#fnref:6" class="footnote-back-ref">↩</a></p></li>
<li id="fn:7"><p>Rees, Jonathan A. "JAR's Scheme 48 Page". Jonathan A. Rees. Mumble.net. Retrieved 2018-12-05. <a href="http://mumble.net/~jar/s48/" target="_blank">http://mumble.net/~jar/s48/</a> <a href="#fnref:7" class="footnote-back-ref">↩</a></p></li>
<li id="fn:8"><p>Shivers, Olin. "Olin Shivers: History of T". PaulGraham.com. Retrieved 2018-12-05. <a href="http://www.paulgraham.com/thist.html" target="_blank">http://www.paulgraham.com/thist.html</a> <a href="#fnref:8" class="footnote-back-ref">↩</a></p></li>
</ol>

Scheme 48 open-in-new

Scheme 48