# T (programming language)

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Dialect of the Scheme programming language

T Paradigms Multi-paradigm: object-oriented, imperative, functional, meta Family Lisp Designed by Jonathan A. Rees Norman I. Adams Developers same First appeared 1982; 44 years ago (1982) Final release 3.0 / August 1, 1984; 41 years ago (1984-08-01) Typing discipline dynamic, strong Platform Cross-platform OS Cross-platform Website mumble.net/~jar/tproject Influenced by Scheme Influenced EuLisp, Joule

**T** is a [dialect](/source/Dialect_(computing)) of the [Scheme](/source/Scheme_(programming_language)) [programming language](/source/Programming_language) developed in the early 1980s by Jonathan A. Rees, [Kent M. Pitman](/source/Kent_Pitman), and Norman I. Adams of [Yale University](/source/Yale_University) as an experiment in language design and implementation.[1]

## Rationale

T's purpose is to test the thesis developed by [Guy L. Steele Jr.](/source/Guy_L._Steele_Jr.) and [Gerald Jay Sussman](/source/Gerald_Jay_Sussman) 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 [C](/source/C_(programming_language)) and [BLISS](/source/BLISS), which are usually considered to be inherently more efficient than Lisp on conventional machine architectures. Much of this occurs via an [optimizing compiler](/source/Optimizing_compiler) named Orbit.

T contains some features that modern Scheme lacks. For example, T is [object-oriented](/source/Object-oriented_programming), and it has first-class environments, called *locales*, which can be modified non-locally and used as a module system. T has several extra special forms for [lazy evaluation](/source/Lazy_evaluation) and [flow control](/source/Control_flow), and an equivalent to [Common Lisp](/source/Common_Lisp)'s [setf](/source/Setf_(disambiguation)). T, like Scheme, supports [call-with-current-continuation](/source/Call-with-current-continuation) (call/cc), but it also has a more limited form called catch. From the T manual, a hypothetical implementation of [cons](/source/Cons) could be:

 (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))))

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 [inheritance](/source/Inheritance_(object-oriented_programming)).

Timeline of Lisp dialects v t e 1958 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010 2015 2020 LISP 1, 1.5, LISP 2(abandoned) Maclisp Interlisp MDL Lisp Machine Lisp Scheme R5RS R6RS R7RS small NIL ZIL (Zork Implementation Language) Franz Lisp muLisp Common Lisp ANSI standard Le Lisp MIT Scheme XLISP T Chez Scheme Emacs Lisp AutoLISP PicoLisp Gambit EuLisp ISLISP OpenLisp PLT Scheme Racket newLISP GNU Guile Visual LISP Clojure Arc LFE Hy

## Ports

T was ported to many hardware [platforms](/source/Computing_platform) and [operating systems](/source/Operating_system), including:[2]

- [MIPS](/source/MIPS_architecture): DEC 3100 (pmax), [SGI IRIS](/source/SGI_IRIS)

- [Motorola 68000](/source/Motorola_68000) (m68k): Apollo Domain/OS, [HP/UX](/source/HP%2FUX), Mac/AUX, [NeXT](/source/NeXT), [SunOS](/source/SunOS) 3

- [NS320xx](/source/NS320xx) (n32k): [Encore](/source/Encore_Computer) Multimax

- [SPARC](/source/SPARC): SunOS 4 and above, [Solaris](/source/Solaris_(operating_system)), [Unix](/source/Unix) on [Connection Machine](/source/Connection_Machine) 5

- [VAX](/source/VAX): Ultrix

## See also

- [Computer programming portal](https://en.wikipedia.org/wiki/Portal:Computer_programming)

## References

1. **[^](#cite_ref-1)** Slade, Stephen (1987). *The T programming language: a dialect of LISP*. Englewood Cliffs, New Jersey: Prentice-Hall. [ISBN](/source/ISBN_(identifier)) [978-0-13-881905-7](https://en.wikipedia.org/wiki/Special:BookSources/978-0-13-881905-7). [OCLC](/source/OCLC_(identifier)) [16094677](https://search.worldcat.org/oclc/16094677).

1. **[^](#cite_ref-2)** Campbell, Taylor `Riastradh' (7 April 2006). ["T Revival Project"](http://mumble.net/~campbell/t/t.html). *Mumble.net*. Internet Archive Wayback Machine. [Archived](https://web.archive.org/web/20070103020434/http://mumble.net/~campbell/t/t.html) from the original on 2007-01-03. Retrieved 2018-11-18.

## External links

- [Official website](http://mumble.net/~jar/tproject)

- [History of T](http://www.paulgraham.com/thist.html), by Olin Shivers

- [T manual](https://web.archive.org/web/20170515045004/http://repository.readscheme.org/ftp/papers/t_manual.pdf) (PDF) from ReadScheme, via the Internet Archive

v t e Lisp programming Features Automatic storage management Conditionals Dynamic typing Higher-order functions Linked lists Macros M-expressions (deprecated) Read–eval–print loop Recursion S-expressions Self-hosting compiler Tree data structures Object systems Common Lisp Object System (CLOS) CommonLoops Flavors Implementations Standardized Common Lisp Allegro Common Lisp Armed Bear Common Lisp (ABCL) CLISP Clozure CL CMU Common Lisp (CMUCL) Corman Common Lisp Embeddable Common Lisp (ECL) GNU Common Lisp (GCL) LispWorks Macintosh Common Lisp Mocl Movitz Poplog Steel Bank Common Lisp (SBCL) Symbolics Common Lisp Scheme History Bigloo Chez Scheme Chicken Gambit Game Oriented Assembly Lisp (GOAL) GNU Guile Ikarus JScheme Kawa MIT/GNU Scheme MultiLisp Pocket Scheme Racket (features) Scheme 48 SCM SIOD T TinyScheme ISLISP OpenLisp Unstandardized Logo MSWLogo NetLogo StarLogo UCBLogo POP COWSEL (POP-1) POP-2 POP-11 Arc AutoLISP BBN LISP Clojure Dylan (Apple, history) Emacs Lisp EuLisp Franz Lisp, PC-LISP Hy Interlisp Knowledge Engineering Environment *Lisp LeLisp LFE LISP 2 Lisp Machine Lisp Lispkit Lisp Maclisp MDL MLisp newLISP NIL PC-LISP Picolisp Portable Standard Lisp RPL S-1 Lisp SKILL Spice Lisp Zetalisp Operating system List Common Lisp Interface Manager, McCLIM Genera Scsh Hardware Lisp machine TI Explorer Space-cadet keyboard Community of practice Technical standards Scheme Requests for Implementation Common Lisp HyperSpec X3J13 Education Books Common Lisp the Language How to Design Programs (HTDP) On Lisp Practical Common Lisp Structure and Interpretation of Computer Programs (SICP) Curriculum ProgramByDesign Organizations Business Apple Computer Bolt, Beranek and Newman Harlequin Lucid Inc. Symbolics Xanalys Education Massachusetts Institute of Technology (MIT) MIT Computer Science and Artificial Intelligence Laboratory (CSAIL) Stanford Artificial Intelligence Laboratory University of California, Berkeley People Edmund Berkeley Daniel G. Bobrow William Clinger R. Kent Dybvig Matthias Felleisen Robert Bruce Findler Matthew Flatt Phyllis Fox Paul Graham Richard Greenblatt Timothy P. Hart Louis Hodes Mike Levin David Luckham John McCarthy Robert Tappan Morris Joel Moses David Park Steve Russell Richard Stallman Common Lisp Scott Fahlman Richard P. Gabriel Philip Greenspun (10th rule) David A. Moon Kent Pitman Guy L. Steele Jr. Daniel Weinreb Scheme Matthias Felleisen Shriram Krishnamurthi Guy L. Steele Jr. Gerald Jay Sussman Julie Sussman Logo Hal Abelson Denison Bollay Wally Feurzeig Brian Harvey Seymour Papert Mitchel Resnick Cynthia Solomon POP Rod Burstall Robin Popplestone Books Commons Categories: Language • Family

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