Definition: A language that does not allow any destructive operation---one which overwrites data---such as the assignment operation. Purely functional languages are free of side effects, i.e., invoking a function has no effect other than computing the value returned by the function.
Note: From Algorithms and Theory of Computation Handbook, page 5-24, Copyright © 1999 by CRC Press LLC. Appearing in the Dictionary of Computer Science, Engineering and Technology, Copyright © 2000 CRC Press LLC.
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Entry modified 17 December 2004.
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Cite this as:
Algorithms and Theory of Computation Handbook, CRC Press LLC, 1999, "purely functional language", in Dictionary of Algorithms and Data Structures [online], Paul E. Black, ed. 17 December 2004. (accessed TODAY) Available from: https://www.nist.gov/dads/HTML/purelyfnctnl.html