at

At

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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