Spread assignment

In a decomposing assignment, putting ... in front of a variable expands all remaining elements into that variable. This is called expansion assignment.

[x, *y] = [1, 2, 3]
assert x == 1
assert y == [2, 3]
x, *y = (1, 2, 3)
assert x == 1
assert y == (2, 3)

Extract assignment

Extraction assignment is a convenient syntax for localizing specific attributes within a module or record.

{sin; cos; tan} = import "math"

After that, you can use sin, cos, tan locally.

You can do the same with records.

record = {x = 1; y = 2}
{x; y} = record

If you want to expand all, use {*} = record. It is open in OCaml.

record = {x = 1; y = 2}
{*} = records
assert x == 1 and y == 2