Glossary of APL terms

APL literature includes many terms whose meanings, though rigorous, differ slightly from elsewhere. Terms used here but not defined follow normal usage or are defined at FOLDOC¹.

Term	Description
ambivalent	(or nomadic²)(of a dyadic function) permitting its left argument to be elided.
array	data valued object of zero or more orthogonal dimensions in row-major order in which each item is a primitive scalar or another array.
define	create by lexical assignment³ or association⁴ or in an editor⁵.
depth	(of an array) the number of levels of nesting.
derive	create by juxtaposition as a combination of one or two existing arrays or functions with an operator⁶.
dyadic	accepting or requiring two arguments or operands: left and right; having valence of two.
empty	(of an array) having one or more dimensions of length zero.
function	primitive, defined, derived or system operation or mapping that takes zero, one (right) or two (left & right) array valued arguments and may return an array valued result.
matrix	(of a function) applying to matrices.
monadic	accepting or requiring one argument or operand; on the right for a function; on the left for an operator; having valence of one.
nested	(of an array) having one or more items or a prototype which is not a primitive scalar.
niladic	accepting no arguments; having valence of zero.
operator	primitive or defined operation or mapping that takes one (left) or two (left & right) function or array valued arguments (operands) and derives a function.
pervasive	(of a function) applying equally to scalars at any depth.
prototype	(of an array) the type of its first item.
rank	(of an array) number of dimensions. (of a function) ranks of arguments to which it applies.
reduction	application of a function between the items of its right argument thus reducing the rank by one.
scalar	(of a function) applying to scalars. (- extension) replication of a scalar argument to the shape of the other.
shape	(of an array) length of each dimension.
simple	(of a scalar) a single primitive datum. (of an array) composed entirely of primitive scalars.
strand	lexical juxtaposition of array valued names or expressions to form a larger, possibly nested, array⁷.
type	(of an array) array of identical structure in which all numbers are zero and all characters are blanks.
valence	degree or number of arguments or operands of an operation.
vector	(of a function) applying to vectors.
workspace	area of computer memory containing arrays and defined &/or derived operations or a file containing a preserved binary image of such.

-- PhilLast 2009-10-05 14:55:22

CategoryAboutApl

FOLDOC: see Free On-Line Dictionary Of Computing (1)
nomadic: see APLX concepts (2)
define by lexical assignment: assigned←{expression in terms of ⍺ and/or ⍵} (3)
define by lexical association: ⎕FX 'r←a associated w' 'r←expression in terms of a and/or w' (4)
define in an editor: ∇edited or )EDIT edited (5)
derive: derived←∘.,/∘(⍳¨) (6)
strand: stranded←0(1 2)('three' 'four')'five' (7)