T (programming language)

<h2 id="rationale">Rationale</h2>
<p>T's purpose is to test the thesis developed by <a href="/facts/Guy_L._Steele_Jr./amHwRA1l">Guy L. Steele Jr.</a> and <a href="/facts/Gerald_Jay_Sussman/S18E8MNx">Gerald Jay Sussman</a> in their series of papers about Scheme: that Scheme may be used as the basis for a practical programming language of exceptional expressive power, and that implementations of Scheme could perform better than other Lisp systems, and competitively with implementations of programming languages, such as <a href="/facts/C_(programming_language)/Ky2No763">C</a> and <a href="/facts/BLISS/5rYFKqDT">BLISS</a>, which are usually considered to be inherently more efficient than Lisp on conventional machine architectures. Much of this occurs via an <a href="/facts/Optimizing_compiler/JXnv4LUd">optimizing compiler</a> named Orbit.
</p><p>T contains some features that modern Scheme lacks. For example, T is <a href="/facts/Object-oriented_programming/TxNMEcao">object-oriented</a>, and it has first-class environments, called <i>locales</i>, which can be modified non-locally and used as a module system. T has several extra special forms for <a href="/facts/Lazy_evaluation/mD3DxDkc">lazy evaluation</a> and <a href="/facts/Control_flow/2XTDfErC">flow control</a>, and an equivalent to <a href="/facts/Common_Lisp/mq1pRbSF">Common Lisp</a>'s <a href="/facts/Setf_(disambiguation)/ljKHBCqo">setf</a>. T, like Scheme, supports <a href="/facts/Call-with-current-continuation/Uc3bTJWC">call-with-current-continuation</a> (call/cc), but it also has a more limited form called catch. From the T manual, a hypothetical implementation of <a href="/facts/Cons/KTYIDGwz">cons</a> could be:
</p>
 (define-predicate pair?)
 (define-settable-operation (car pair))
 (define-settable-operation (cdr pair))
 (define (cons the-car the-cdr)
         (object nil
                 ((pair? self) t)
                 ((car self) the-car)
                 ((cdr self) the-cdr)
                 (((setter car) self new-car) (set the-car new-car))
                 (((setter cdr) self new-cdr) (set the-cdr new-cdr))))

<p>This example shows that objects in T are intimately related to closures and message-passing. A primitive called join puts two objects together, allowing for something resembling <a href="/facts/Inheritance_(object-oriented_programming)/a7R1xv8n">inheritance</a>.
</p>

<h2 id="ports">Ports</h2>
<p>T was ported to many hardware <a href="/facts/Computing_platform/DmKwp5Bk">platforms</a> and <a href="/facts/Operating_system/8XTuvMh2">operating systems</a>, including:<a class="footnote-ref" id="fnref:2" href="#fn:2"><sup>2</sup></a>
</p>
<ul><li><a href="/facts/MIPS_architecture/efV4KgK4">MIPS</a>: DEC 3100 (pmax), <a href="/facts/SGI_IRIS/Xh1r3yNd">SGI IRIS</a></li>
<li><a href="/facts/Motorola_68000/3p2wt2D6">Motorola 68000</a> (m68k): Apollo Domain/OS, <a href="/facts/HP%2fUX/hIvLDdJF">HP/UX</a>, Mac/AUX, <a href="/facts/NeXT/71CK18lB">NeXT</a>, <a href="/facts/SunOS/oWMcGLqc">SunOS</a> 3</li>
<li><a href="/facts/NS320xx/zCXoyxzh">NS320xx</a> (n32k): <a href="/facts/Encore_Computer/9wRoEkTb">Encore</a> Multimax</li>
<li><a href="/facts/SPARC/m7KhEtET">SPARC</a>: SunOS 4 and above, <a href="/facts/Solaris_(operating_system)/KPfT98EJ">Solaris</a>, <a href="/facts/Unix/0pNL2seI">Unix</a> on <a href="/facts/Connection_Machine/wxUPNe4r">Connection Machine</a> 5</li>
<li><a href="/facts/VAX/N3r13IHH">VAX</a>: Ultrix</li></ul>
<h2 id="see-also">See also</h2>
<ul>
<li>Computer programming portal</li></ul>

<h2 id="external-links">External links</h2>
<ul><li><a href="http://mumble.net/~jar/tproject">Official website</a></li>
<li><a href="http://www.paulgraham.com/thist.html">History of T</a>, by Olin Shivers</li>
<li><a href="https://web.archive.org/web/20170515045004/http://repository.readscheme.org/ftp/papers/t_manual.pdf">T manual</a> (PDF) from ReadScheme, via the Internet Archive</li></ul>

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

<ol>
<li id="fn:1"><p>Slade, Stephen (1987). The T programming language: a dialect of LISP. Englewood Cliffs, New Jersey: Prentice-Hall. ISBN 978-0-13-881905-7. OCLC 16094677. <a href="978-0-13-881905-7" target="_blank">978-0-13-881905-7</a> <a href="#fnref:1" class="footnote-back-ref">↩</a></p></li>
<li id="fn:2"><p>Campbell, Taylor `Riastradh' (7 April 2006). "T Revival Project". Mumble.net. Internet Archive Wayback Machine. Archived from the original on 2007-01-03. Retrieved 2018-11-18. <a href="http://mumble.net/~campbell/t/t.html" target="_blank">http://mumble.net/~campbell/t/t.html</a> <a href="#fnref:2" class="footnote-back-ref">↩</a></p></li>
</ol>

T (programming language) open-in-new

T (programming language)