maps

README

maps

Go utilities for working with maps.

Requires Go 1.25+

Functions

Inverse

Swaps keys and values in a map. Both keys and values must be comparable.

m := map[string]int{"a": 1, "b": 2}
inverted := maps.Inverse(m) // map[int]string{1: "a", 2: "b"}

Keys (Deprecated)

Deprecated: Use slices.Collect(maps.Keys(m)) from the standard library instead.

Retrieves keys from a map as a slice. The order of keys is not guaranteed.

// Old way (deprecated)
keys := maps.Keys(m)

// New way (recommended)
keys := slices.Collect(maps.Keys(m))

Values (Deprecated)

Deprecated: Use slices.Collect(maps.Values(m)) from the standard library instead.

Retrieves values from a map as a slice. The order of values is not guaranteed.

// Old way (deprecated)
values := maps.Values(m)

// New way (recommended)
values := slices.Collect(maps.Values(m))

Migration Guide

Go 1.25+ includes a standard library maps package with iterator-based Keys() and Values() functions. To migrate:

1. Import both maps and slices from the standard library
2. Replace maps.Keys(m) with slices.Collect(maps.Keys(m))
3. Replace maps.Values(m) with slices.Collect(maps.Values(m))

The Keys and Values functions in this package will be removed in a future version.

Documentation

Index

• func Inverse[K comparable, V comparable](in map[K]V) map[V]K
• func Keys[M ~map[K]V, K comparable, V any](m M) []K
• func Values[M ~map[K]V, K comparable, V any](m M) []V

Examples

• Keys (StandardLibrary)
• Values (StandardLibrary)

Functions

func Inverse

func Inverse[K comparable, V comparable](in map[K]V) map[V]K

func Keys

func Keys[M ~map[K]V, K comparable, V any](m M) []K

Keys returns all keys from the map as a slice.

Deprecated: Use slices.Collect(maps.Keys(m)) from the standard library instead. This function will be removed in a future version.

Example (StandardLibrary)

Example showing how to use the standard library maps.Keys with slices.Collect. This is the recommended approach going forward.

m := map[int]string{1: "one", 2: "two", 3: "three"}

// New way: use standard library
keys := slices.Collect(stdmaps.Keys(m))
slices.Sort(keys)

// Output can't be guaranteed due to map iteration order,
// but this demonstrates the pattern
_ = keys

func Values

func Values[M ~map[K]V, K comparable, V any](m M) []V

Values returns all values from the map as a slice.

Deprecated: Use slices.Collect(maps.Values(m)) from the standard library instead. This function will be removed in a future version.

Example (StandardLibrary)

Example showing how to use the standard library maps.Values with slices.Collect. This is the recommended approach going forward.

m := map[int]string{1: "one", 2: "two", 3: "three"}

// New way: use standard library
values := slices.Collect(stdmaps.Values(m))
slices.Sort(values)

// Output can't be guaranteed due to map iteration order,
// but this demonstrates the pattern
_ = values