Beside: Difference between revisions

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{{Built-in|Beside|∘}}, '''Compose''' or '''After''' is a [[primitive operator]]. It shares the glyph <source lang=apl inline>∘</source> with [[Bind]]. Called [[Dyadic function|dyadically]] with function operands <source lang=apl inline>f</source> and <source lang=apl inline>g</source>, it uses <source lang=apl inline>g</source> [[Monadic function|monadically]] to pre-processes the right argument before applying <source lang=apl inline>f</source> to the given left argument and pre-processed right argument. Called [[Monadic function|monadically]] with operands <source lang=apl inline>f</source> and <source lang=apl inline>g</source>, it applies <source lang=apl inline>f</source> to the result of applying <source lang=apl inline>g</source> to the argument.
{{Built-in|Beside|∘}}, '''Compose''' or '''After''' is a [[primitive operator]]. It shares the glyph [[Jot]] (<syntaxhighlight lang=apl inline>∘</syntaxhighlight>) with [[Bind]]. Called [[Dyadic function|dyadically]] with function [[operand]]s <syntaxhighlight lang=apl inline>f</syntaxhighlight> and <syntaxhighlight lang=apl inline>g</syntaxhighlight>, it uses <syntaxhighlight lang=apl inline>g</syntaxhighlight> [[Monadic function|monadically]] to pre-processes the right argument before applying <syntaxhighlight lang=apl inline>f</syntaxhighlight> to the given left argument and pre-processed right argument. Called [[Monadic function|monadically]] with operands <syntaxhighlight lang=apl inline>f</syntaxhighlight> and <syntaxhighlight lang=apl inline>g</syntaxhighlight>, it applies <syntaxhighlight lang=apl inline>f</syntaxhighlight> to the result of applying <syntaxhighlight lang=apl inline>g</syntaxhighlight> to the argument.


In usage, <source lang=apl inline>X f∘g Y</source> is equivalent to <source lang=apl inline>X f g Y</source>, and <source lang=apl inline>f∘g Y</source> is equivalent to <source lang=apl inline>f g Y</source>. Thus, beside can be defined as the [[dop]] <source lang=apl inline>{⍺←⊢ ⋄ ⍺ ⍺⍺ ⍵⍵ ⍵}</source>.
In usage, <syntaxhighlight lang=apl inline>X f∘g Y</syntaxhighlight> is equivalent to <syntaxhighlight lang=apl inline>X f g Y</syntaxhighlight>, and <syntaxhighlight lang=apl inline>f∘g Y</syntaxhighlight> is equivalent to <syntaxhighlight lang=apl inline>f g Y</syntaxhighlight>. Thus, beside can be defined as the [[dop]] <syntaxhighlight lang=apl inline>{⍺←⊢ ⋄ ⍺ ⍺⍺ ⍵⍵ ⍵}</syntaxhighlight>.
 
== Examples ==
When used [[monadic]]ally, <syntaxhighlight lang=apl inline>f∘g</syntaxhighlight> behaves the same as an [[atop]]:
 
<syntaxhighlight lang=apl>
      -∘÷ 2
¯0.5
      ⍝ same as
      -(÷2)
¯0.5
</syntaxhighlight>
 
When used [[dyadic]]ally, <syntaxhighlight lang=apl inline>f∘g</syntaxhighlight> forms a dyadic [[hook]]:
 
<syntaxhighlight lang=apl>
      'oy'≡∘⌽'yo'
1
      ⍝ same as
      'oy'≡⌽'yo'
1
</syntaxhighlight>
 
When used monadically with [[Commute]], <syntaxhighlight lang=apl inline>f∘g</syntaxhighlight> forms a monadic [[hook]]:
<syntaxhighlight lang=apl>
      ≡∘⌽⍨'UwU'
1
      ⍝ same as this, because operators are left-associative, unlike functions which are right-associative
      (≡∘⌽)⍨'UwU'
1
      ⍝ same as
      'UwU'≡⌽'UwU'
1
</syntaxhighlight>
This is equivalent to the dyadic behaviour of [[Withe]] <syntaxhighlight lang=apl inline>f⍩g</syntaxhighlight>.


== External links ==
== External links ==
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=== Documentation ===
=== Documentation ===


* [http://help.dyalog.com/17.1/#Language/Primitive%20Operators/Composition%20Form%20I.htm Dyalog] (monadic), [http://help.dyalog.com/17.1/#Language/Primitive%20Operators/Composition%20Form%20IV.htm Dyalog] (dyadic)
* [https://help.dyalog.com/latest/#Language/Primitive%20Operators/Beside.htm Dyalog]
 


{{APL built-ins}}
{{APL built-ins}}[[Category:Primitive operators]][[Category:Composition operators]]

Latest revision as of 06:20, 28 February 2024

Beside (), Compose or After is a primitive operator. It shares the glyph Jot () with Bind. Called dyadically with function operands f and g, it uses g monadically to pre-processes the right argument before applying f to the given left argument and pre-processed right argument. Called monadically with operands f and g, it applies f to the result of applying g to the argument.

In usage, X f∘g Y is equivalent to X f g Y, and f∘g Y is equivalent to f g Y. Thus, beside can be defined as the dop {⍺←⊢ ⋄ ⍺ ⍺⍺ ⍵⍵ ⍵}.

Examples

When used monadically, f∘g behaves the same as an atop:

      -∘÷ 2 
¯0.5
      ⍝ same as
      -(÷2)
¯0.5

When used dyadically, f∘g forms a dyadic hook:

      'oy'≡∘⌽'yo'
1
      ⍝ same as
      'oy'≡⌽'yo'
1

When used monadically with Commute, f∘g forms a monadic hook:

      ≡∘⌽⍨'UwU'
1
      ⍝ same as this, because operators are left-associative, unlike functions which are right-associative
      (≡∘⌽)⍨'UwU'
1
      ⍝ same as
      'UwU'≡⌽'UwU'
1

This is equivalent to the dyadic behaviour of Withe f⍩g.

External links

Lessons

Documentation


APL built-ins [edit]
Primitives (Timeline) Functions
Scalar
Monadic ConjugateNegateSignumReciprocalMagnitudeExponentialNatural LogarithmFloorCeilingFactorialNotPi TimesRollTypeImaginarySquare Root
Dyadic AddSubtractTimesDivideResiduePowerLogarithmMinimumMaximumBinomialComparison functionsBoolean functions (And, Or, Nand, Nor) ∙ GCDLCMCircularComplexRoot
Non-Scalar
Structural ShapeReshapeTallyDepthRavelEnlistTableCatenateReverseRotateTransposeRazeMixSplitEncloseNestCut (K)PairLinkPartitioned EnclosePartition
Selection FirstPickTakeDropUniqueIdentityStopSelectReplicateExpandSet functions (IntersectionUnionWithout) ∙ Bracket indexingIndexCartesian ProductSort
Selector Index generatorGradeIndex OfInterval IndexIndicesDealPrefix and suffix vectors
Computational MatchNot MatchMembershipFindNub SieveEncodeDecodeMatrix InverseMatrix DivideFormatExecuteMaterialiseRange
Operators Monadic EachCommuteConstantReplicateExpandReduceWindowed ReduceScanOuter ProductKeyI-BeamSpawnFunction axis
Dyadic BindCompositions (Compose, Reverse Compose, Beside, Withe, Atop, Over) ∙ Inner ProductDeterminantPowerAtUnderRankDepthVariantStencilCutDirect definition (operator)
Quad names Index originComparison toleranceMigration levelAtomic vector