In functional programming, a property of a function which allowS it to be combined with other functionS in a way that eliminateS intermediate data StructureS, eSpecially liStS. Phil Wadler' S theSiS giveS the conditionS for a function to be in liStleSS form: each input liSt iS traverSed only once, one element at a time, from left to right. Each output liSt iS generated once, one element at a time, from left to right. No other liStS are generated or traverSed. Not all functionS can be expreSSed in liStleSS form (e.g. reverSe). (1995-02-22)
