A Turing tarpit (or Turing tar-pit) is any programming language or computer interface that allows for flexibility in function but is difficult to learn and use because it offers little or no support for common tasks. The phrase was coined in 1982 by Alan Perlis in the Epigrams on Programming:
54. Beware of the Turing tar-pit in which everything is possible but nothing of interest is easy.
In any Turing complete language, it is possible to write any computer program, so in a very rigorous sense nearly all programming languages are equally capable. Showing that theoretical ability is not the same as usefulness in practice, Turing tarpits are characterized by having a simple abstract machine that requires the user to deal with many details in the solution of a problem. At the extreme opposite are interfaces which can perform very complex tasks with little human intervention but become obsolete if requirements change slightly.
Some esoteric programming languages, such as Brainfuck, are specifically referred to as "Turing tarpits" because they deliberately implement the minimum functionality necessary to be classified as Turing complete languages. Using such languages is a form of mathematical recreation: programmers can work out how to achieve basic programming constructs in an extremely difficult but mathematically Turing-equivalent language.
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- Perlis, A (September 1982). "Epigrams on Programming". ACM SIGPLAN Notices (Yale University) 17 (9): 7–13. doi:10.1145/947955.1083808. Archived from the original on 1996-03-26. Retrieved 28 August 2015.
- "Exploring the depths of a Turing tarpit". practicingruby.com. 7 February 2013.
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- Esoteric Topics in Computer Programming, Cat's Eye Technologies, Canada. ("They present the programmer with the challenge, intrigue, and entertainment of looking at known algorithms and concepts in a whole new light.")
- G. Fischer, A.C. Lemke, "Constrained Design Processes: Steps Toward Convivial Computing", Technical Report CU-CS-369-87, Colorado University, USA.
- E.L. Hutchins, J.D. Hollan, D.A. Norman, "Direct Manipulation Interfaces". In User Centered System Design. New Perspectives on Human–Computer Interaction (1986).