At: Difference between revisions
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If <code>y</code> is an atom not in the domain of <code>x</code>, at returns the [[null?|null value]] for <code>x</code>'s type (except in kona). |
If <code>y</code> is an atom not in the domain of <code>x</code>, at returns the [[null?|null value]] for <code>x</code>'s type (except in kona). |
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[[Category:Verbs]] |
[[Category:Verbs]] |
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[[Category:Primitives]] |
[[Category:Primitives]] |
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Revision as of 06:14, 9 July 2022
At
x@y
at is a primitive that unifies list indexing, function application, and dictionary lookup into a single concept. Syntactically, it can be expressed in three equivalent ways: x@y (using @ as a verb), x y (juxtaposition of nouns), and x[y] (M-expression).
"abc"[1]
"b"
{1+2*x}@3
7
(`a`b!0 1)`b
1
If y is an atom not in the domain of x, at returns the null value for x's type (except in kona).