lower_bound: Find First Element with Key '>=' Query

In Immutables: Fast and Functional Data Structures

Find First Element with Key >= Query

Description

Find First Element with Key >= Query

Usage

lower_bound(x, key)

Arguments

x	An ordered_sequence.
key	Query key.

Details

lower_bound() finds the first element with key ⁠>= key⁠. This includes an exact key match when present, which is useful for starting equality or inclusive range scans.

Value

A list with fields:

• found: logical flag.

• index: one-based position of the first match, or NULL.

• value: matched element, or NULL.

• key: matched key, or NULL.

See Also

upper_bound()

Examples

x <- ordered_sequence("a", "b", "c", keys = c(1, 2, 2))
lower_bound(x, 2)
lower_bound(x, 10)

Immutables documentation built on April 29, 2026, 1:06 a.m.