List::Util

Native Rust implementation built into the interpreter. Runtime: PP. See original documentation for the full Perl reference.

Provides list utility functions (first, sum, min, max, reduce, etc.)

Perl Equivalent

This module provides Rust-native implementations of functions from List::Util. Since PetaPerl does not support XS, these are implemented directly in Rust.

Functions like first, any, all, none, notall, and reduce in Perl take a block argument. These use the &@ prototype which tells the parser to treat func { block } @list syntax correctly.

Synopsis

use List::Util qw(sum min max first any all reduce uniq);

my $total = sum @numbers;
my $smallest = min @numbers;
my $largest  = max @numbers;

my $found = first { $_ > 10 } @numbers;
my $has_neg = any { $_ < 0 } @numbers;
my $all_pos = all { $_ > 0 } @numbers;

my $product = reduce { $a * $b } @numbers;
my @unique  = uniq @strings;

Functions

all

Returns true if all elements in LIST satisfy the given block. Sets $_ to each element in turn. Short-circuits on the first false result.

any

Returns true if any element in LIST satisfies the given block. Sets $_ to each element in turn. Short-circuits on the first true result.

first(&@)

Returns the first element in LIST for which the block returns true. Sets $_ to each element in turn. Returns undef if no match is found.

head

Returns the first SIZE elements from LIST. If SIZE is negative, returns all but the last -SIZE elements.

max

Returns the numerically largest element of LIST. Returns undef for an empty list.

maxstr

Returns the string-wise maximum of LIST. Uses gt comparison. Returns undef for an empty list.

mesh

Returns a flat list of interleaved elements from the given array references. Also available as mesh_longest. Shorter arrays are padded with undef.

See also: mesh_shortest, zip, zip_shortest

mesh_longest

mesh_shortest

Like mesh, but stops at the shortest input array instead of padding shorter arrays with undef.

min

Returns the numerically smallest element of LIST. Returns undef for an empty list.

minstr

Returns the string-wise minimum of LIST. Uses lt comparison. Returns undef for an empty list.

none

Returns true if no element in LIST satisfies the given block. The logical negation of any. Short-circuits on the first true result.

notall

Returns true if not all elements in LIST satisfy the given block. The logical negation of all. Short-circuits on the first false result.

pairfirst

Like pairgrep, but returns only the first matching pair (as a 2-element list) and stops searching. Returns an empty list if no pair matches.

pairgrep

Calls BLOCK for each consecutive pair of elements in LIST, with $a set to the key and $b set to the value. Returns the key/value pairs for which the block returns true. In scalar context, returns the count of matching pairs.

pairkeys

Returns a list of the first values (keys) of each pair in LIST. LIST is treated as an even-sized list of key/value pairs.

pairmap

Calls BLOCK for each consecutive pair of elements in LIST, with $a set to the key and $b set to the value. Returns a flat list of all values returned by each block invocation.

pairs

Returns a list of array references, each containing two items from the given list. It is a convenient shortcut to operating on even-sized lists of key/value pairs.

If the list has an odd number of elements, the final pair will have undef as the value. Each returned array reference is a plain ARRAY ref (not blessed).

pairvalues

Returns a list of the second values (values) of each pair in LIST. LIST is treated as an even-sized list of key/value pairs.

product

Returns the numeric product of all elements in LIST. Returns undef for an empty list, 1 for a single element.

reduce

Reduces LIST by calling BLOCK in a scalar context, with $a and $b set to successive pairs of values. Returns the final value of $a, or undef for an empty list. For a one-element list, returns that element without calling the block.

reductions

Like reduce, but returns a list of all intermediate accumulator values as well as the final result. The first element is always the first value of the list.

sample

Returns COUNT random elements from LIST without replacement. Each element can be selected at most once.

If COUNT exceeds the list size, returns the entire list shuffled. Croaks if COUNT is negative.

shuffle

Returns the elements of LIST in a random order.

Uses the Fisher-Yates shuffle algorithm for uniform distribution.

sum

Returns the numeric sum of all elements in LIST. Returns undef for an empty list.

sum0

Like sum, but returns 0 instead of undef for an empty list.

tail

Returns the last SIZE elements from LIST. If SIZE is negative, returns all but the first -SIZE elements.

uniq

Filters a list of values to remove subsequent duplicates, as determined by a string comparison. Preserves the order of first occurrence. Also available as uniqstr.

Compares values as strings to determine uniqueness. In scalar context, returns the number of unique elements. undef is treated as a distinct value (not equal to empty string).

uniqint

Filters a list of values to remove subsequent duplicates, as determined by an integer comparison. Values are truncated to integers before comparing. Preserves the order of first occurrence.

In scalar context, returns the number of unique elements.

uniqnum

Filters a list of values to remove subsequent duplicates, as determined by a numeric comparison. Preserves the order of first occurrence.

Compares values numerically. 0 and -0 are considered equal. NaN values are considered equal to each other. In scalar context, returns the number of unique elements.

uniqstr

unpairs

The inverse of pairs. Takes a list of array references and returns a flat list of their elements. Each array ref contributes its first two elements (key and value).

zip

Returns a list of array references, each containing one element from each input array. Also available as zip_longest. Shorter arrays are padded with undef.

See also: zip_shortest, mesh, mesh_shortest

zip_longest

zip_shortest

Like zip, but stops at the shortest input array instead of padding shorter arrays with undef.

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