[ - Begin List Literal
Tags: literal , array
The beginners' page has a more thorough explanation of Jelly syntax and tokenization.
Begin a comma-separated list literal. These are not required for a depth-1 literal, but can nest.
[1,2] is equivalent to
1,2. You can nest these to create multidimensional lists (such as
[1,0],[0,1] for the 2×2 identity matrix) or create singleton lists (such as
). Square brackets must be balanced. Note that
 doesn't work; instead, use
⁸ (Chain Left Argument / Empty List) if in a niladic chain.