Function array: Difference between revisions

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A '''function array''', or '''fnarray''', is a value that is conceptually an [[array]] of [[function]]s. It can be applied to [[argument]]s, which applies each function independently and gives an array of results. Several languages that don't ordinarily support placing a function in an array have function arrays as a special construct: [[Dyalog APL]], [[dzaima/APL]], and [[Nial]], which uses the name "atlas".
A '''function array''', or '''fnarray''', is a value that is conceptually an [[array]] of [[function]]s. It can be applied to [[argument]]s, which applies each function independently and gives an array of results. Several languages that don't ordinarily support placing a function in an array have function arrays as a special construct: [[Dyalog APL]], [[dzaima/APL]], and [[Nial]], which uses the name "atlas".


In dzaima/APL and Nial function arrays are constructed by the vector form of [[array notation]], allowing only rank-1 function arrays. In Dyalog APL they can be produced by taking a member of an array of [[namespace]]s that all contain that member, each with its own function value. <source lang=apl inline>fnarray</source> in the [[dfns workspace]] wraps this functionality in an operator.<ref>[[Dfns workspace]]. [https://dfns.dyalog.com/n_fnarray.htm <source lang=apl inline>fnarray</source>] ― Array of functions.</ref>
In dzaima/APL and Nial function arrays are constructed by the vector form of [[array notation]], allowing only rank-1 function arrays. In Dyalog APL they can be produced by taking a member of an array of [[namespace]]s that all contain that member, each with its own function value. <syntaxhighlight lang=apl inline>fnarray</source> in the [[dfns workspace]] wraps this functionality in an operator.<ref>[[Dfns workspace]]. [https://dfns.dyalog.com/n_fnarray.htm <syntaxhighlight lang=apl inline>fnarray</source>] ― Array of functions.</ref>


The [[wikipedia:FP (programming language)|FP]] language features a "function composition" construction that applies like a function array. In the [[I]] language, which has first-class functions, lists may be applied to arguments, and apply each element independently, so that a list of functions also behaves like a function array.
The [[wikipedia:FP (programming language)|FP]] language features a "function composition" construction that applies like a function array. In the [[I]] language, which has first-class functions, lists may be applied to arguments, and apply each element independently, so that a list of functions also behaves like a function array.

Revision as of 21:11, 10 September 2022

A function array, or fnarray, is a value that is conceptually an array of functions. It can be applied to arguments, which applies each function independently and gives an array of results. Several languages that don't ordinarily support placing a function in an array have function arrays as a special construct: Dyalog APL, dzaima/APL, and Nial, which uses the name "atlas".

In dzaima/APL and Nial function arrays are constructed by the vector form of array notation, allowing only rank-1 function arrays. In Dyalog APL they can be produced by taking a member of an array of namespaces that all contain that member, each with its own function value. <syntaxhighlight lang=apl inline>fnarray</source> in the dfns workspace wraps this functionality in an operator.[1]

The FP language features a "function composition" construction that applies like a function array. In the I language, which has first-class functions, lists may be applied to arguments, and apply each element independently, so that a list of functions also behaves like a function array.

References

APL features [edit]
Built-ins Primitives (functions, operators) ∙ Quad name
Array model ShapeRankDepthBoundIndex (Indexing) ∙ AxisRavelRavel orderElementScalarVectorMatrixSimple scalarSimple arrayNested arrayCellMajor cellSubarrayEmpty arrayPrototype
Data types Number (Boolean, Complex number) ∙ Character (String) ∙ BoxNamespaceFunction array
Concepts and paradigms Conformability (Scalar extension, Leading axis agreement) ∙ Scalar function (Pervasion) ∙ Identity elementComplex floorArray ordering (Total) ∙ Tacit programming (Function composition, Close composition) ∙ GlyphLeading axis theoryMajor cell searchFirst-class function
Errors LIMIT ERRORRANK ERRORSYNTAX ERRORDOMAIN ERRORLENGTH ERRORINDEX ERRORVALUE ERROREVOLUTION ERROR