at

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).