Go proposes generic collection types for standard library in Go 1.28

New Generic Collections Proposed

The Go Collections working group has released proposals for new generic collection types to be included in the standard library, targeting Go 1.28. This effort seeks to expand the available data structures beyond the current limited offerings, which primarily consist of built-in slices and maps, and the heap for priority queues.

Addressing Current Gaps

Currently, Go's standard library lacks common collection types like sets and ordered maps. Sets are typically implemented using `map[T]bool` or `map[T]struct{}`, while binary tree-based ordered maps and sets are entirely absent. The new proposals aim to fill these gaps by introducing standardized, generic implementations.

Leveraging Recent Language Features

The ability to add these new collection types is made possible by the introduction of generics in Go 1.18 and iterators in Go 1.23. These language features allow library-defined types to achieve ergonomics comparable to built-in types, enabling common operations on slices and maps to be expressed as library function calls.

Key Proposed Additions

Specific proposals include `hash/maphash.Hasher` for custom hash functions and equivalence relations, `container/hash.Map[K,V]` for a hash-based map utilizing these custom hash functions, and `container/hash.Set[T]` for a hash-based set. These additions are intended to establish conventions for future API developments within the standard library.