teamai-test/.teamai/skills/common/golang-popular-libraries/references/stdlib.md

Standard Library - New & Experimental

The Go standard library continues to evolve with v2 packages and experimental features. Prefer these over external libraries when available.

V2 Packages (API Breaking Changes)

math/rand/v2 (Go 1.22+) Improved random number generation with better algorithms (ChaCha8, PCG). Auto-seeded, no more rand.Seed() needed.

encoding/json/v2 (experimental stdlib package behind GOEXPERIMENT=jsonv2) Next-generation JSON encoding/decoding. Evaluate deliberately; most production code should keep encoding/json unless the project explicitly opts into the experiment.

New Packages (Promoted from x/exp)

slices (Go 1.21+) Generic slice operations: BinarySearch, Clone, Compact, Compare, Contains, Delete, Insert, Replace, Reverse, Sort. Reduces the need for external libraries.

maps (Go 1.21+) Generic map operations: Clone, Copy, DeleteFunc, Equal, EqualFunc. Go 1.23+ adds iterator helpers such as All, Collect, Insert, Keys, and Values.

cmp (Go 1.21+) Comparison utilities: Compare, Or, Ordered. Used with the slices/maps packages.

iter (Go 1.23+) Iterator support for sequences. Enables range-over functions and integrates with slices/maps methods.

unique (Go 1.23+) Value canonicalization and interning. Efficient deduplication of comparable values.

log/slog (Go 1.21+) Structured logging for the standard library. Alternative to external logging libraries for many use cases.

weak (Go 1.24+) Weak references for garbage collection. Useful for caches and observers.

structs (Go 1.23+) Structure layout control and introspection.

golang.org/x (Official Extensions)

golang.org/x/oauth2 OAuth2 client implementation. Supports multiple providers (Google, GitHub, etc.). Official OAuth2 client.

golang.org/x/crypto Additional cryptographic algorithms: bcrypt, blowfish, scrypt, ssh, acme (Let's Encrypt), pbkdf2.

golang.org/x/net Network utilities: websocket, context, proxy, trace, http2, ipv4/ipv6, netutil.

golang.org/x/text Text processing: encoding, unicode, cases, search, language (language tag parsing and matching).

golang.org/x/sync Extended synchronization: errgroup, singleflight, semaphore.

golang.org/x/sys/cpu CPU feature detection for architecture-specific optimized code. Use it only when dispatching between measured implementations; prefer portable stdlib code first.