Primitive function: Difference between revisions

A primitive function is a [[function]] defined by the language. Outside of the array community, such functions may be called "builtin" or "intrinsic" functions. In APL, each is represented with a single [[glyph]]; in other languages, such as those restricted to [https://en.wikipedia.org/wiki/ASCII ASCII] characters, they may use multiple characters ("bigraphs" and "trigraphs" are combinations of two and three characters, respectively).

Other parts of APL which are written with a single glyph include [[Primitive operator|primitive operators]] and [[Quad]].

Early APL implementations divided primitives into [[Scalar function|scalar functions]], which apply one element at a time, and [[Mixed function|mixed functions]], which do not. Modern APLs universally retain the terminology "scalar function" but may deemphasize its opposite "mixed function" or subdivide it further. Two prominent subcategories of functions are [[Structural function|structural functions]], which rearrange elements of the argument or its subarrays without regard to their values, and [[Set functions|set functions]], which return a result or manipulate arrays based on which cells or elements are equal to other cells or elements.

A function is distinct from the [[glyph]] used to denote it. Different APLs, or even one APL (using [[Migration level]]) might use the same glyph for multiple functions, or different glyphs for identical or similar functions. The term "function" can, depending on context, refer either to an [[ambivalent]] function which can be applied with one or two arguments, or the [[Monad|monadic]] or [[Dyad|dyadic]] function obtained by restricting that function to either one or two arguments specifically.