Function styles: Difference between revisions

Another kind of function which can be created by the programmer are tacit functions, so named because they do not include any mention of their arguments, leaving them unsaid. Languages with tacit functions call the other types of functions, which do refer to arguments as part of a function body, "explicit" functions. Tacit functions are created as values: [[derived function]]s and [[train]]s are two kinds of tacit function. For example <syntaxhighlight lang=apl inline>+/</syntaxhighlight>, [[Plus]] [[Reduce]], is a derived function that can be created in any APL. However, early APLs usually did not allow [[assign]]ing a name to such functions: the only ways to call them were to write the function out explicitly and to define an equivalent explicit function. Function assignment was proposed by Iverson in 1981<ref>[[Ken Iverson]] and Peter Wooster. [https://dl.acm.org/doi/abs/10.1145/390007.805349 A function definition operator] at [[APL81]].</ref> and added to [[Dyalog APL]] in 1986. Since the promotion of tacit programming by [[J]] in the 90s it is present in all new APLs.