> ## Documentation Index > Fetch the complete documentation index at: https://docs.sifr.sh/llms.txt > Use this file to discover all available pages before exploring further. # Sifr Standard Library: Built-in Modules Overview Guide > A complete reference to the sifr.* standard library namespace: how to import modules, why bare CPython names are rejected, and what every module provides. Sifr ships a comprehensive standard library under the `sifr.*` namespace. Every module is designed with Rust-backed safety guarantees — predictable ownership, explicit error types, and no hidden global mutation. Because Sifr compiles to Rust rather than running on the CPython interpreter, the standard library is its own surface; it is not a thin wrapper around CPython's built-in modules. For a compact inventory of every module currently shipped in `stdlib/sifr`, see the [Module Index](/stdlib/module-index). ## How to Import Use `from sifr. import ` for every standard library import: ```python theme={null} from sifr.math import sqrt from sifr.json import loads, dumps from sifr.encoding import decode, encode from sifr.unicode import normalize from sifr.i18n import LocaleId from sifr.task import TaskGroup from sifr.net import connect_tcp ``` **Bare CPython module names are not supported.** Importing `math`, `json`, `os`, `collections`, `codecs`, `unicodedata`, `locale`, or any other CPython stdlib name directly triggers error [`SIFR-IMPORT-0008`](/errors/SIFR-IMPORT-0008) and the compiler suggests the correct `sifr.*` replacement. ```python theme={null} # ❌ Rejected — raises SIFR-IMPORT-0008 from math import sqrt import json # ✅ Correct from sifr.math import sqrt from sifr.json import loads ``` `import sifr.math` (module-object form) is also unsupported in the current release. Always import the specific symbols you need using `from sifr. import `. If a real user-defined or third-party top-level module named `math`, `json`, or similar exists in your project, the normal top-level resolution imports it without a diagnostic. The [`SIFR-IMPORT-0008`](/errors/SIFR-IMPORT-0008) error only fires when no real top-level module matches the bare name. ## Available Modules | Module | Description | | --------------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | `sifr.math` | Mathematical functions: `sqrt`, `floor`, `ceil`, `log`, trigonometric helpers, and numeric constants. | | `sifr.json` | JSON serialization and deserialization. `loads` returns a typed `JsonValue`; `dumps` serializes Sifr values to JSON strings. Malformed input raises `JSONDecodeError`. | | `sifr.re` | Regular expression matching and substitution with Unicode-aware patterns. | | `sifr.datetime` | Date and time values, durations, timezone-aware timestamps, and formatting. | | `sifr.random` | Cryptographically seeded random number generation. | | `sifr.hashlib` | Hash functions: SHA-256, SHA-512, MD5 (legacy), BLAKE3, and HMAC construction. | | `sifr.uuid` | UUID generation (`uuid4`) and parsing for v4 and v5 identifiers. | | Module | Description | | ------------------ | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ | | `sifr.collections` | `Counter`, `deque`, `defaultdict`, and set helpers (`set_from_list`, `set_union`, `set_intersection`). Safe indexing returns `Option` instead of raising `KeyError` or `IndexError`. | | Module | Description | | -------------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | `sifr.io` | `open_text` for text files with a required explicit encoding, and binary file I/O. Text-mode `open()` without `encoding=` is unsupported ([`SIFR-IO-0801`](/errors/SIFR-IO-0801)). | | `sifr.pathlib` | `Path` construction, joining, extension manipulation, existence checks, and directory traversal. | | `sifr.os` | File and directory operations: `remove_file`, `rename`, `mkdir`, `listdir`, and stat helpers. | | `sifr.env` | Read and write process environment variables as explicit typed values. | | `sifr.sys` | Process arguments (`argv`), exit helpers, and platform query values. | | Module | Description | | --------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------- | | `sifr.encoding` | Byte/text boundary conversions: `encode`, `decode`, codec descriptors (`ascii()`, `latin1()`), error handlers, and typed `DecodeError` / `EncodeError`. | | `sifr.unicode` | Unicode 17.0.0 data: `normalize` (NFC/NFD/NFKC/NFKD), `name`, `category`, `graphemes`, `words`, and scalar properties. | | `sifr.i18n` | Locale-aware formatting: `LocaleId`, `NumberFormatter`, `PluralRules`, `bundle_from_mo_bytes`, and `translator` with explicit fallback chains. | Concurrency has its own docs section. Start with the [Concurrency Overview](/language/concurrency), then use the [Concurrency API](/concurrency/api) for module reference. | Module | Description | | --------------- | --------------------------------------------------------------------------------------------------------------------------- | | `sifr.task` | Structured task management: `TaskGroup`, `TaskHandle[T, E]`, scoped `spawn`, `timeout`, `deadline`, `gather`, and `select`. | | `sifr.sync` | Same-process synchronization: `Shared[T]`, `channel`, `bounded_channel`, `Lock`, `RwLock`, `Semaphore`, and `Notify`. | | `sifr.parallel` | CPU-parallel map over owned data: `map`, `try_map`, `Pool`, and `PoolConfig`. | | `sifr.runtime` | Structured runtime diagnostics: `DiagnosticEvent`, `DiagnosticLevel`, `emit_diagnostic`, and `DiagnosticError`. | | `sifr.resource` | Deterministic cleanup helpers: `nullcontext` and `NullContext[T]`. | | `sifr.ipc` | Typed IPC substrate for Sifr-native process workers: `SchemaId`, `FrameKind`, `BackpressurePolicy`, and `IpcError`. | | Module | Description | | ----------- | ----------------------------------------------------------------------------------------------------------------------------- | | `sifr.net` | Async TCP client and server primitives: `connect_tcp` and `listen_tcp`. | | `sifr.http` | HTTP protocol substrate: methods, status codes, `HeaderMap`, `RequestHead`, `ResponseHead`, `BodyStream`, and cookie parsing. | | `sifr.tls` | Rustls-backed TLS client configurations and encrypted streams over `sifr.net`. | | `sifr.url` | Typed URL parsing, query-string manipulation, and percent-encoding helpers. | | Module | Description | | -------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------- | | `sifr.process` | Subprocess management: `run`, `spawn`, `output`, `output_text`, shell helpers, and async variants. Handles are owned resources with typed `ProcessError`. | | `sifr.signal` | Structured shutdown signals: `ctrl_c`, `shutdown_stream`, `SIGINT`, `SIGTERM`, and `strsignal`. | | `sifr.time` | Monotonic and wall-clock time, sleep, and interval helpers. | | `sifr.logging` | Structured log emission with levels (`DEBUG`, `INFO`, `WARN`, `ERROR`) and typed diagnostic events. | ## What Sifr Does Not Expose Several CPython-shaped names are intentionally absent because they rely on global mutable state or interpreter-specific behavior that conflicts with Sifr's safety model: * `asyncio` event-loop objects and loop-policy mutation * `threading.Lock`, `queue.Queue`, and `multiprocessing.*` * `codecs.register`, `locale.setlocale`, and `gettext.install` * `signal.signal` and `set_wakeup_fd` for arbitrary handler registration Each of these has a typed, ownership-safe equivalent in the `sifr.*` namespace. See the individual module pages for details.