Standard library tour

The standard library is plain .nu source. You pull it in with $-imports. No separate package step is necessary. It has three layers:

Layer	Path	Contents
`core`	`stdlib/core/`	Built into every program's assumptions: strings, vectors, Option/Result, memory helpers
`std`	`stdlib/std/`	The general-purpose standard library: collections, I/O, time, threads, crypto primitives
`ext`	`stdlib/ext/`	Higher-level, optional modules: HTTP, JSON, package management, MCP

Every module is plain-text and readable. The fastest way to see a module's exact function signatures: use nurl_read_stdlib (via the NURL MCP server) or open the file under stdlib/ directly.

Core

Module	Contents
`string.nu`	the managed `String` type and its operations
`vec.nu`	`Vec[T]`, a growable array
`option.nu` / `result.nu`	combinators for `?T` and `!T E` — see Error handling
`slice.nu`	slice helpers
`mem.nu`	low-level allocation helpers
`box.nu` / `cell.nu` / `pair.nu`	small owned-value wrappers
`char.nu`	character classification
`io.nu`	basic input/output
`errors.nu`	shared error-value shapes
`symtab.nu` / `posix.nu`	compiler/runtime-facing helpers

hashmap.nu, btree.nu, ordmap.nu (insertion-ordered map), set.nu, deque.nu, heap.nu, bitset.nu, lru.nu — plus arena.nu for bump-allocated batches, and arc.nu / rc.nu for shared ownership (Arc is thread-safe, Rc is single-threaded — see Concurrency).

Numbers and encoding

int.nu, float.nu, floatbits.nu, bigint.nu, decimal.nu, fft.nu for numeric work; encode.nu and utf8.nu for text encoding; fmt.nu for formatted output.

I/O and the operating system

fs.nu (filesystem), bufio.nu (buffered I/O), path.nu, process.nu, args.nu, env.nu (ext/), signal.nu, term.nu, progress.nu, fswatch.nu.

Time and concurrency

time.nu, thread.nu, channel.nu, async.nu, async_ffi.nu — see Concurrency for the full picture.

Networking

net.nu, dns.nu, udp.nu, unixsock.nu, url.nu, tls.nu, tls_server.nu, tls_verify.nu in std/; the HTTP/1.1 and HTTP/2 stack (http.nu, http_server.nu, http_router.nu, http_middleware.nu, http2_*.nu, and more), websocket.nu, mqtt.nu in ext/. See Networking for a guided tour.

Cryptography

aes_gcm.nu, chacha20poly1305.nu, ecdsa_p256.nu, ed25519.nu, x25519.nu, the hash_*.nu family (SHA-1/2, MD5, BLAKE2b, BLAKE3), hkdf.nu, pbkdf2.nu, scrypt.nu, rsa.nu, minisign.nu, subtle.nu (constant-time comparisons), x509.nu / x509_gen.nu in std/; crypto.nu, jwt.nu, http_jwt.nu in ext/. See Cryptography.

Data formats and serialization

json.nu, msgpack.nu, cbor.nu, protobuf.nu, toml.nu, yaml.nu, xml.nu, csv.nu, serde.nu (a Serialize trait), zip.nu, tar.nu, compress.nu, deflate.nu.

protobuf.nu provides checked Protocol Buffers wire readers and writers for all scalar types, borrowed byte/submessage views, UTF-8 strings, packed fields and groups. Message schemas remain in application code. See the protobuf guide for the API, ownership contract, limits and examples.

Packages and the registry

manifest.nu, resolver.nu, semver.nu, lockfile.nu, registry_index.nu, pkg_fetch.nu, pkg_publish.nu, update_check.nu — the pieces nurlpkg is built from. See Editor and tooling.

Diagnostics and dev tools

bench.nu, log.nu, trace.nu, panic.nu (see Error handling), sort.nu, cmp.nu, random.nu, rng.nu, lifeguard.nu (false-positive suppression for failure detectors), dos.nu (abuse-resistance limits), nurldoc.nu.

Distributed computing and embedded

stdlib/net/ and stdlib/dist/ build a peer-to-peer stack — encrypted transport, NAT traversal, membership/failure detection, and CRDTs — on top of the socket layer above. See Distributed computing. stdlib/hal/ holds hardware-facing code (now an ESP32 memory-mapped I/O layer) for embedded targets — see Embedded targets. Both are advanced, opt-in layers.

Networking
Cryptography
Distributed computing and Embedded targets
Runnable examples for many of these modules are in examples/ — see Next steps.