@lang:unique

Remove duplicates from an array, preserving first-occurrence order.

On-chain (@lang:unique!): Uses canonical ABI equality by default, or a custom equality predicate, preserving first-occurrence order.

Returns: array

Syntax

@lang:unique(arr equal?)

Arguments

Name	Type	Description
`arr`	`array`	Source array
`[equal]`	`helper`	Equality predicate for generic values

On-chain face (@unique!)

Keep the first occurrence of each value, preserving input order. Word arrays use uniqueWords with ordered = false. Strings, bytes, tuples, and nested arrays use uniqueValues with canonical ABI equality by default: the complete value must match, including every tuple field and nested element. An optional named boolean predicate overrides equality. Neither path requires sorted input.

Inputs may be homogeneous literals, live fixed-size or dynamic arrays, or nested on-chain collection helpers. An untyped empty literal defaults to uint256[]. Generic duplicate removal performs up to O(n²) comparisons, so keep live arrays bounded when transaction gas matters.

Examples

load lang

set $safe 0x44fA8E6f47987339850636F88629646662444217

assert @unique!(@sort!($safe::!{getOwners()(address[])})) == 0x1122

# Strings need no explicit equality callback.
assert @len!(@unique!(["alice" "bob" "alice"])) == 2