Stdlib Index (Map)

Overview

After constructing portable applications targeting WASI and native platforms, 42 you now stand at the threshold of Zig’s standard library—a curated collection of approximately 70 top-level modules and 30+ directories spanning data structures, I/O, cryptography, compression, and compiler internals. std.zig

This chapter serves as your map: a navigational index that orients you within zig/lib/std/ for version 0.15.2, showing where to find functionality and how the library categories align with the deep-dive chapters ahead.

Unlike tutorial chapters, this is a reference guide—no code examples, just organized pointers. Use it to locate modules quickly, understand the stdlib’s taxonomy, and jump to the detailed treatment in Chapters 44–52. 44 Think of it as the table of contents for Zig’s batteries-included philosophy.

Learning Goals

• Navigate the physical layout of zig/lib/std/ with confidence, distinguishing top-level files from subdirectories. std
• Identify which stdlib components handle collections, I/O, formatting, compression, time, processes, and debugging. 44
• Recognize the relationship between a module’s filesystem path and its import name (e.g., std.ArrayList maps to array_list.zig). array_list.zig
• Use this index as a springboard to detailed API chapters without getting lost in 100+ source files. 44

Stdlib at a Glance

The standard library ships as part of the Zig compiler installation and resides at zig/lib/std/. Its root directory contains approximately:

• 70 files providing individual modules (e.g., array_list.zig, json.zig, log.zig)
• 30+ subdirectories grouping related functionality (e.g., crypto/, compress/, fs/, math/)
• 1 entry point: std.zig, which re-exports the public API surface

When you write @import("std"), the compiler loads std.zig, which then executes pub const ArrayList = @import("array_list.zig") and similar for each public symbol. This flat-namespace design means std.ArrayList and std.json sit at the same level, even though some implementations span multiple files in subdirectories.

Directory Tree (Selective View)

Below is an ASCII tree showing key directories and representative files. This is not exhaustive (some directories contain 20+ files), but it highlights landmarks for orientation.

std/ ──► Build/ ──► Cache.zig, Fuzz.zig, Module.zig, Step.zig, Watch.zig, WebServer.zig, abi.zig
           │
           ├──► Cache/ ──► DepTokenizer.zig, Directory.zig, Path.zig
           │
           ├──► Step/  ──► CheckFile.zig, CheckObject.zig, Compile.zig, ConfigHeader.zig, Fail.zig,
           │              Fmt.zig, InstallArtifact.zig, InstallDir.zig, InstallFile.zig, ObjCopy.zig,
           │              Options.zig, RemoveDir.zig, Run.zig, TranslateC.zig, UpdateSourceFiles.zig, WriteFile.zig
           │
           └──► Watch/ ──► FsEvents.zig

       └──► Io/ ──► DeprecatedReader.zig, DeprecatedWriter.zig, Reader.zig, Writer.zig, counting_reader.zig
           │
           ├──► fixed_buffer_stream.zig, test.zig, tty.zig
           │
           └──► Reader/ ──► Limited.zig, test.zig

       └──► Random/ ──► Ascon.zig, ChaCha.zig, Isaac64.zig, Pcg.zig, RomuTrio.zig, Sfc64.zig, SplitMix64.zig
           │
           ├──► Xoroshiro128.zig, Xoshiro256.zig, benchmark.zig, test.zig, ziggurat.zig

       └──► Target/ ──► Query.zig, aarch64.zig, amdgcn.zig, arc.zig, arm.zig, avr.zig, bpf.zig, csky.zig
           │
           ├──► generic.zig, hexagon.zig, lanai.zig, loongarch.zig, m68k.zig, mips.zig, msp430.zig
           │
           ├──► nvptx.zig, powerpc.zig, propeller.zig, riscv.zig, s390x.zig, sparc.zig, spirv.zig
           │
           ├──► ve.zig, wasm.zig, x86.zig, xcore.zig, xtensa.zig

       └──► Thread/ ──► Condition.zig, Futex.zig, Pool.zig, ResetEvent.zig, RwLock.zig, Semaphore.zig, WaitGroup.zig
           │
           ├──► Mutex/ ──► Recursive.zig
           │
           └──► Mutex.zig

       └──► builtin/ ──► assembly.zig

       └──► c/ ──► darwin.zig, dragonfly.zig, freebsd.zig, haiku.zig, netbsd.zig, openbsd.zig, serenity.zig, solaris.zig

       └──► compress/ ──► flate.zig, lzma.zig, lzma2.zig, xz.zig, zstd.zig
           │
           ├──► flate/ ──► BlockWriter.zig, Compress.zig, Decompress.zig, HuffmanEncoder.zig, Lookup.zig, Token.zig, testdata/
           │
           ├──► lzma/  ──► decode/, decode.zig, test.zig, testdata/, vec2d.zig
           │
           ├──► lzma2/ ──► decode.zig
           │
           ├──► xz/    ──► block.zig, test.zig, testdata/
           │
           └──► zstd/  ──► Decompress.zig

       └──► crypto/ ──► Certificate.zig, Sha1.zig, aegis.zig, aes.zig, aes_gcm.zig, aes_ocb.zig, argon2.zig, ascon.zig, bcrypt.zig
           │
           ├──► benchmark.zig, blake2.zig, blake3.zig, chacha20.zig, cmac.zig, codecs.zig, ecdsa.zig, errors.zig, ff.zig
           │
           ├──► ghash_polyval.zig, hash_composition.zig, hkdf.zig, hmac.zig, isap.zig, keccak_p.zig, md5.zig, ml_kem.zig
           │
           ├──► modes.zig, pbkdf2.zig, phc_encoding.zig, poly1305.zig, salsa20.zig, scrypt.zig, sha2.zig, sha3.zig
           │
           ├──► siphash.zig, test.zig, timing_safe.zig, tlcsprng.zig, tls.zig
           │
           ├──► 25519/ ──► curve25519.zig, ed25519.zig, edwards25519.zig, field.zig, ristretto255.zig, scalar.zig, x25519.zig
           │
           ├──► aes/    ──► aesni.zig, armcrypto.zig, soft.zig
           │
           ├──► codecs/ ──► asn1/, asn1.zig, base64_hex_ct.zig
           │
           ├──► pcurves/ ──► common.zig, p256/, p256.zig, p384/, p384.zig, secp256k1/, secp256k1.zig, tests/
           │
           └──► tls/    ──► Client.zig

       └──► debug/ ──► Coverage.zig, Dwarf.zig, FixedBufferReader.zig, Info.zig, MemoryAccessor.zig, Pdb.zig, SelfInfo.zig
           │
           ├──► no_panic.zig, simple_panic.zig
           │
           └──► Dwarf/ ──► abi.zig, call_frame.zig, expression.zig

       └──► dwarf/ ──► AT.zig, ATE.zig, EH.zig, FORM.zig, LANG.zig, OP.zig, TAG.zig

       └──► fmt/ ──► float.zig, parse_float.zig
           │
           ├──► parse_float/ ──► FloatInfo.zig, FloatStream.zig, common.zig, convert_eisel_lemire.zig
           │
           ├──► convert_fast.zig, convert_hex.zig, convert_slow.zig, decimal.zig, parse.zig

       └──► fs/ ──► AtomicFile.zig, Dir.zig, File.zig, get_app_data_dir.zig, path.zig, test.zig, wasi.zig

       └──► hash/ ──► Adler32.zig, auto_hash.zig, benchmark.zig, cityhash.zig, fnv.zig, murmur.zig, verify.zig, wyhash.zig
           │
           └──► xxhash.zig
           │
           └──► crc/ ──► crc.zig, impl.zig, test.zig

       └──► heap/ ──► FixedBufferAllocator.zig, PageAllocator.zig, SmpAllocator.zig, ThreadSafeAllocator.zig, WasmAllocator.zig
           │
           ├──► arena_allocator.zig, debug_allocator.zig, memory_pool.zig, sbrk_allocator.zig

       └──► http/ ──► ChunkParser.zig, Client.zig, HeadParser.zig, HeaderIterator.zig, Server.zig, test.zig

       └──► json/ ──► JSONTestSuite_test.zig, Scanner.zig, Stringify.zig, dynamic.zig, dynamic_test.zig
           │
           ├──► hashmap.zig, hashmap_test.zig, scanner_test.zig, static.zig, static_test.zig, test.zig

       └──► math/ ──► acos.zig, acosh.zig, asin.zig, asinh.zig, atan.zig, atan2.zig, atanh.zig, cbrt.zig, copysign.zig
           │
           ├──► cosh.zig, expm1.zig, expo2.zig, float.zig, frexp.zig, gamma.zig, gcd.zig, hypot.zig
           │
           ├──► ilogb.zig, isfinite.zig, isinf.zig, isnan.zig, isnormal.zig, iszero.zig, lcm.zig, ldexp.zig, log.zig
           │
           ├──► log10.zig, log1p.zig, log2.zig, log_int.zig, modf.zig, nextafter.zig, pow.zig, powi.zig
           │
           ├──► scalbn.zig, signbit.zig, sinh.zig, sqrt.zig, tanh.zig
           │
           ├──► big/ ──► int.zig, int_test.zig
           │
           └──► complex/ ──► abs.zig, acos.zig, acosh.zig, arg.zig, asin.zig, asinh.zig, atan.zig, atanh.zig
                          └──► conj.zig, cos.zig, cosh.zig, exp.zig, ldexp.zig, log.zig, pow.zig, proj.zig, sin.zig
                          └──► sinh.zig, sqrt.zig, tan.zig, tanh.zig

       └──► mem/ ──► Allocator.zig

       └──► meta/ ──► trailer_flags.zig

       └──► net/ ──► test.zig

       └──► os/ ──► emscripten.zig, freebsd.zig, linux.zig, plan9.zig, uefi.zig, wasi.zig, windows.zig
           │
           ├──► linux/ ──► IoUring.zig, aarch64.zig, arm.zig, bpf.zig, bpf/, hexagon.zig, io_uring_sqe.zig, ioctl.zig
           │
           ├──► loongarch64.zig, m68k.zig, mips.zig, mips64.zig, powerpc.zig, powerpc64.zig
           │
           ├──► riscv32.zig, riscv64.zig, s390x.zig, seccomp.zig, sparc64.zig, syscalls.zig
           │
           ├──► test.zig, thumb.zig, tls.zig, vdso.zig, x86.zig, x86_64.zig
           │
           └──► plan9/ ──► x86_64.zig
           │
           └──► uefi/ ──► device_path.zig, hii.zig, pool_allocator.zig, protocol.zig, protocol/, status.zig
           │
           └──► windows/ ──► advapi32.zig, crypt32.zig, kernel32.zig, lang.zig, nls.zig, ntdll.zig
                          └──► ntstatus.zig, sublang.zig, test.zig, tls.zig, win32error.zig, ws2_32.zig

       └──► posix/ ──► test.zig

       └──► process/ ──► Child.zig

       └──► sort/ ──► block.zig, pdq.zig

       └──► testing/ ──► FailingAllocator.zig

       └──► time/ ──► epoch.zig

       └──► unicode/ ──► (empty, API in `unicode.zig`)

       └──► valgrind/ ──► cachegrind.zig, callgrind.zig, memcheck.zig

       └──► tar/ ──► Writer.zig, test.zig
           └──► testdata/

       └──► tz/ ──► (empty)

       └──► zon/ ──► Serializer.zig, parse.zig, stringify.zig

       └──► zig/ ──► Ast.zig, AstGen.zig, AstRlAnnotate.zig, BuiltinFn.zig, Client.zig, ErrorBundle.zig
           │
           ├──► LibCDirs.zig, LibCInstallation.zig, Parse.zig, Server.zig, WindowsSdk.zig
           │
           ├──► Zir.zig, Zoir.zig, ZonGen.zig, c_builtins.zig, c_translation.zig
           │
           ├──► number_literal.zig, parser_test.zig, perf_test.zig, primitives.zig
           │
           ├──► string_literal.zig, system.zig, target.zig, tokenizer.zig
           │
           ├──► Ast/ ──► Render.zig
           │
           ├──► llvm/ ──► BitcodeReader.zig, Builder.zig, bitcode_writer.zig, ir.zig
           │
           └──► system/ ──► NativePaths.zig, arm.zig, darwin.zig, linux.zig, windows.zig, x86.zig
                          └──► darwin/

Module Categories

The following sections group stdlib functionality by purpose, mapping each category to its detailed chapter. Use this as a quick-reference guide when you know what you need but not where it lives.

Specialized Modules (Not Covered in Detail)

Some stdlib components are highly specialized or primarily internal to the compiler. They appear in the directory tree but aren’t the focus of the upcoming chapters:

Import Conventions

Zig’s stdlib uses a flat namespace at the top level: std.ArrayList, std.HashMap, std.json, etc. Internally, some modules split across subdirectories (crypto/, compress/), but the public API is re-exported through a single .zig file in the root.

Examples:

• std.crypto.aes → defined in crypto/aes/, re-exported by crypto.zig
• std.compress.flate → defined in compress/flate/, re-exported by compress.zig
• std.fs.Dir → defined in fs/Dir.zig, re-exported by fs.zig

Navigating the Source

To explore the stdlib yourself:

1. Locate your Zig installation: Run zig env and note lib_dir. #Command-line-flags

2. Browse : Use ls, tree, or your editor’s file explorer.

3. Read top-level files first: std.zig shows what’s public; individual .zig files contain implementation.

4. Check subdirectories for depth: Directories like crypto/, compress/, math/ house specialized code. crypto

What’s Next

This index orients you, but the real learning happens in the detailed chapters:

• Chapter 44: Collections and algorithms—ArrayList, HashMap, PriorityQueue, sorting. 44
• Chapter 45: Text, formatting, Unicode—std.fmt, std.ascii, Base64. 45
• Chapter 46: I/O and streams—std.Io, std.fs, adapters. 46
• Chapter 47: Time, logging, progress—std.time, std.log, std.Progress. 47
• Chapter 48: Process and environment—std.process, std.posix. 48
• Chapter 49: Compression and archives—std.compress, std.tar, std.zip. 49
• Chapter 50: Random, math, hashing—std.Random, std.math, std.crypto. 50
• Chapter 51: Mem and meta utilities—std.mem, std.meta. 51
• Chapter 52: Debug and Valgrind—std.debug, std.valgrind. 52

Each chapter provides code examples, API walkthroughs, and practical guidance. Use this index to jump directly to the module you need.

Notes & Caveats

• This index reflects Zig 0.15.2. Future versions may reorganize modules or rename exports. v0.15.2
• Not all stdlib components are stable—some are marked experimental or subject to breaking changes between releases.
• The compiler’s own internals (std.zig.*, std.Build.*) are advanced topics. Start with user-facing APIs like collections and I/O before diving into AST manipulation. zig

Exercises

• Run zig env and navigate to lib_dir/std/, then ls the root to see all top-level modules. Pick three you’ve never heard of and read their first 20 lines to understand their purpose.
• Open std.zig in your editor and trace how std.ArrayList is defined. (Hint: pub const ArrayList = @import("array_list.zig").ArrayList;)
• Grep the stdlib for pub fn to count how many public functions exist across all modules. Use this to gauge the stdlib’s scope.
• Compare the directory structure of crypto/ vs. compress/. Notice how both contain subdirectories for specific algorithms, illustrating Zig’s modular organization philosophy.

Caveats, alternatives, edge cases

• Some modules have both a .zig file and a directory (e.g., fmt.zig and fmt/). The file typically re-exports the directory’s contents or provides a high-level API. fmt.zig
• The stdlib does not include a package manager or registry integration (that’s external tooling). It focuses on language-level utilities and OS abstractions.
• Third-party libraries are not part of std. You’ll use build.zig.zon and std.Build.dependency() to fetch them.