A representation of integers as functions invented by {Alonzo Church}, inventor of {lambda-calculus}. The integer N is represented as a ef="module.php?name=Lexikon&file=search&eid=1&query=higher-order function">higher-order function which applies a given function N times to a given expression. In the {pure lambda-calculus} there are no constants but numbers can be represented by Church integers. A ef="module.php?name=Lexikon&file=search&eid=1&query=Haskell">Haskell function to return a given Church integer could be written: church n = c where c f x = if n == 0 then x else c' f (f x) where c' = church (n-1) A function to turn a Church integer into an ordinary integer: unchurch c = c (+1) 0 See also ef="module.php?name=Lexikon&file=search&eid=1&query=von Neumann integer">von Neumann integer. (1994-11-29)

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