upper_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

upper_bound(x, key)

Arguments

x	An ordered_sequence.
key	Query key.

Details

upper_bound() finds the first element with key ⁠> key⁠. This skips exact key matches, which is useful for exclusive range endpoints and for finding the position immediately after a duplicate-key run.

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

lower_bound()

Examples

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

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