A reduction strategy which delays evaluation of function arguments until they are needed because they are arguments to a primitive function or a conditional. Call-by-need is one part of lazy evaluation. The term first appears in Chris Wadsworth' s thesis "Semantics and Pragmatics of the Lambda calculus" (Oxford, 1971, p. 183). It was used later, by J. Vuillemin in his thesis (Stanford, 1973). (1995-05-27)
