Difference between revisions of "Compose"
m (Text replacement  "Category:Primitive operators" to "Category:Primitive operatorsCategory:Composition operators") 

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In [[Ken Iverson]]'s designs [[Rationalized APL]], [[A Dictionary of APL]], and the [[J]] language, the composition (<source lang=apl inline>⍤</source>) or Compose (<source lang=j inline>&</source>) refers to a different kind of composition, the [[Over]] operator.  In [[Ken Iverson]]'s designs [[Rationalized APL]], [[A Dictionary of APL]], and the [[J]] language, the composition (<source lang=apl inline>⍤</source>) or Compose (<source lang=j inline>&</source>) refers to a different kind of composition, the [[Over]] operator.  
−  More recently, the term "composition" is used in [[Dyalog APL]] to refer to any of a family of operators including [[Beside]] and [[Bind]] (<source lang=apl inline>∘</source>), [[Commute]] and [[Constant]] (<source lang=apl inline>⍨</source>), [[Atop]] (<source lang=apl inline>⍤</source>), and [[Over]] (<source lang=apl inline>⍥</source>).<ref>[[Marshall Lochbaum]]. [https://dyalog.tv/Dyalog19/?v=czWC4tjwzOQ Tacit Techniques with Dyalog version 18.0 Operators] ([https://www.dyalog.com/uploads/conference/dyalog19/presentations/D04_Tacit_Techniques.zip slides]) at [[Dyalog '19]].</ref> [[Extended Dyalog APL]] and [[dzaima/APL]] add to this list the operators [[Under]] (<source lang=apl inline>⍢</source>) and [[Reverse Compose]] (<source lang=apl inline>⍛</source>).  +  More recently, the term "[[function compositioncomposition]]" is used in [[Dyalog APL]] to refer to any of a family of operators including [[Beside]] and [[Bind]] (<source lang=apl inline>∘</source>), [[Commute]] and [[Constant]] (<source lang=apl inline>⍨</source>), [[Atop]] (<source lang=apl inline>⍤</source>), and [[Over]] (<source lang=apl inline>⍥</source>).<ref>[[Marshall Lochbaum]]. [https://dyalog.tv/Dyalog19/?v=czWC4tjwzOQ Tacit Techniques with Dyalog version 18.0 Operators] ([https://www.dyalog.com/uploads/conference/dyalog19/presentations/D04_Tacit_Techniques.zip slides]) at [[Dyalog '19]].</ref> [[Extended Dyalog APL]] and [[dzaima/APL]] add to this list the operators [[Under]] (<source lang=apl inline>⍢</source>) and [[Reverse Compose]] (<source lang=apl inline>⍛</source>). 
== References ==  == References ==  
<references />  <references />  
{{APL builtins}}[[Category:Primitive operators]][[Category:Composition operators]]  {{APL builtins}}[[Category:Primitive operators]][[Category:Composition operators]] 
Latest revision as of 20:01, 24 June 2020
∘

Compose (∘
) or Composition is the most common name for the primitive dyadic operator denoted with a Jot (∘
) introduced by NARS and included in the Dyalog APL family. On the APL Wiki, Compose is divided into its two cases, Beside when both operands are functions, and Bind when one is a function and the other an array.
Composition assembles functions and arguments to form derived functions. This provides the glue with which to put together functions and arguments so that operator's arguments can be more complex than single functions.^{[1]}
In Ken Iverson's designs Rationalized APL, A Dictionary of APL, and the J language, the composition (⍤
) or Compose (&
) refers to a different kind of composition, the Over operator.
More recently, the term "composition" is used in Dyalog APL to refer to any of a family of operators including Beside and Bind (∘
), Commute and Constant (⍨
), Atop (⍤
), and Over (⍥
).^{[2]} Extended Dyalog APL and dzaima/APL add to this list the operators Under (⍢
) and Reverse Compose (⍛
).
References
 ↑ Carl M. Cheney. APL*PLUS Nested Arrays System (NARS reference manual). STSC. 1981.
 ↑ Marshall Lochbaum. Tacit Techniques with Dyalog version 18.0 Operators (slides) at Dyalog '19.