Consider this simple Haskell definition, of a function which counts the number of occurrences of a given word w in a string:

count w = length . filter (==w) . words

This is an example of “point-free” programming style, where we build a function by composing others, and make heavy use of higher-order functions such as filter. Point-free programming is rightly popular: used appropriately, it makes for concise and readable definitions, which are well suited to equational reasoning in the style of Bird and Meertens [2]. It’s also a natural way to assemble programs from components, and closely related to connecting programs via pipes in the UNIX shell.


Stream Function Output Event Full Adder Input Event Loop Body 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.


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Copyright information

© Springer-Verlag Berlin Heidelberg 2005

Authors and Affiliations

  • John Hughes
    • 1
  1. 1.Department of Computer Science and EngineeringChalmers University of TechnologyGöteborgSweden

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