Stop: Difference between revisions

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(Also in A+, where it returns an empty vector of symbols)
(⊢⍨)
 
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In other dialects, monadic <syntaxhighlight lang=apl inline>⊣</syntaxhighlight> is the [[identity function]], exactly like <syntaxhighlight lang=apl inline>⊢</syntaxhighlight>. This redundancy means that it can be redefined without losing any primitive functionality. However, pairing both dyadic functions with the identity may be useful in constructing [[ambivalent]] functions, particularly in [[tacit]] programming. In [[April]], monadic <syntaxhighlight lang=apl inline>⊣</syntaxhighlight> ("Empty") returns its argument is returned as a shy result, giving it the properties of both Stop and the identity.
In other dialects, monadic <syntaxhighlight lang=apl inline>⊣</syntaxhighlight> is the [[identity function]], exactly like <syntaxhighlight lang=apl inline>⊢</syntaxhighlight>. This redundancy means that it can be redefined without losing any primitive functionality. However, pairing both dyadic functions with the identity may be useful in constructing [[ambivalent]] functions, particularly in [[tacit]] programming. In [[April]], monadic <syntaxhighlight lang=apl inline>⊣</syntaxhighlight> ("Empty") returns its argument is returned as a shy result, giving it the properties of both Stop and the identity.
In dialects where <syntaxhighlight lang=apl inline>⊣</syntaxhighlight> does not return the argument when used monadically, the effect can be achieved with <syntaxhighlight lang=apl inline>⊢⍨</syntaxhighlight> using the [[commute]] operator.


== Documentation ==
== Documentation ==

Latest revision as of 08:17, 5 March 2024

⊣

Stop (⊣) (in SHARP APL and APLX), Hide (in GNU APL and Kap), or Null (in A+) is a primitive monadic function that ignores its argument and returns a non-printing value. It shares the left tack glyph with Left Identity. The nature of the returned value can vary: for example an empty matrix is used in SAX and APLX, while GNU APL uses the scalar 0 but returns it as a shy result (or "committed"). In SHARP APL's initial implementation of ⊣, Stop returned "no result", so that attempting to use its result would be an error.[1]

In other dialects, monadic ⊣ is the identity function, exactly like ⊢. This redundancy means that it can be redefined without losing any primitive functionality. However, pairing both dyadic functions with the identity may be useful in constructing ambivalent functions, particularly in tacit programming. In April, monadic ⊣ ("Empty") returns its argument is returned as a shy result, giving it the properties of both Stop and the identity.

In dialects where ⊣ does not return the argument when used monadically, the effect can be achieved with ⊢⍨ using the commute operator.

Documentation

References

  1. ↑ "Language Extensions of May 1983". SATN-45, 1983-05-02.
APL built-ins [edit]
Primitives (Timeline) Functions
Scalar
Monadic Conjugate ∙ Negate ∙ Signum ∙ Reciprocal ∙ Magnitude ∙ Exponential ∙ Natural Logarithm ∙ Floor ∙ Ceiling ∙ Factorial ∙ Not ∙ Pi Times ∙ Roll ∙ Type ∙ Imaginary ∙ Square Root ∙ Round
Dyadic Add ∙ Subtract ∙ Times ∙ Divide ∙ Residue ∙ Power ∙ Logarithm ∙ Minimum ∙ Maximum ∙ Binomial ∙ Comparison functions ∙ Boolean functions (And, Or, Nand, Nor) ∙ GCD ∙ LCM ∙ Circular ∙ Complex ∙ Root
Non-Scalar
Structural Shape ∙ Reshape ∙ Tally ∙ Depth ∙ Ravel ∙ Enlist ∙ Table ∙ Catenate ∙ Reverse ∙ Rotate ∙ Transpose ∙ Raze ∙ Mix ∙ Split ∙ Enclose ∙ Nest ∙ Cut (K) ∙ Pair ∙ Link ∙ Partitioned Enclose ∙ Partition
Selection First ∙ Pick ∙ Take ∙ Drop ∙ Unique ∙ Identity ∙ Stop ∙ Select ∙ Replicate ∙ Expand ∙ Set functions (Intersection ∙ Union ∙ Without) ∙ Bracket indexing ∙ Index ∙ Cartesian Product ∙ Sort
Selector Index generator ∙ Grade ∙ Index Of ∙ Interval Index ∙ Indices ∙ Deal ∙ Prefix and suffix vectors
Computational Match ∙ Not Match ∙ Membership ∙ Find ∙ Nub Sieve ∙ Encode ∙ Decode ∙ Matrix Inverse ∙ Matrix Divide ∙ Format ∙ Execute ∙ Materialise ∙ Range
Operators Monadic Each ∙ Commute ∙ Constant ∙ Replicate ∙ Expand ∙ Reduce ∙ Windowed Reduce ∙ Scan ∙ Outer Product ∙ Key ∙ I-Beam ∙ Spawn ∙ Function axis ∙ Identity (Null, Ident)
Dyadic Bind ∙ Compositions (Compose, Reverse Compose, Beside, Withe, Atop, Over) ∙ Inner Product ∙ Determinant ∙ Power ∙ At ∙ Under ∙ Rank ∙ Depth ∙ Variant ∙ Stencil ∙ Cut ∙ Direct definition (operator) ∙ Identity (Lev, Dex)
Quad names Index origin ∙ Comparison tolerance ∙ Migration level ∙ Atomic vector
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