Documentation

Weft 0.3.33 — language, stdlib, agents, telecom, devops.

Your app / script ↑ Optional modules telecom · mold · ml · tokensave · cache · retry ... (registry → vendor/) ↑ Stdlib (70 pkgs) llm · http · web · db · fs · sh · mcp · sysinfo ... (in the binary) ↑ Language + VM Result/? · match · enum · closures · channels (lex → parse → compile → run)

Get started

Tutorial Your first hour with Weft. Install, write, run.

beginner

Cookbook 22 paste-ready recipes — searchable on this site.

recipes

Install apt, dnf, macOS, Windows, from source.

setup

Language

Language reference Full syntax, types, closures, enums, match, defer, Result. Syntax cheatsheet One-page quick reference. Error handling Result, ?, context, bail, ensure. Concurrency map/filter fan-out, spawn, channels, race, timeout.

Standard library

Stdlib reference All 70 packages with examples.

http

json

llm

LLM providers OpenAI, Anthropic, Ollama, vLLM — one env switch.

llm

agents

Local LLMs Ollama and vLLM setup for offline use. Web & HTMX HTTP servers, static files, SSE, forms, cookies. CLI tools Flags, subcommands, prompts, exit codes. Data & SQL SQLite, Postgres, CSV, table transforms. DevOps & sysops sysinfo, proc, netutil, shell, runbooks. Charts & viz SVG/HTML charts from data.

Agents & AI

Ecosystem map How llm, mold, ml, tokensave, and telecom fit together. mold — structured output Validate LLM JSON, JSON Schema, tool params. ml — embeddings & RAG Vectors, cosine similarity, RAG index. Fine-tuning Private training, LoRA, presets, air-gapped deployment.

Telecom

telecom module IVA voice agents, STT/TTS, call flows, DTMF, queues, CDR.

IVA

STT

TTS

FreeSWITCH ESL TCP client for real-time call control.

ESL

FreeSWITCH

Asterisk ARI REST + WebSocket for Asterisk call control.

ARI

Asterisk

Packages & modules

Package registry Browse, search, and install packages. API docs for every export. Package manager Install, vendor, lockfiles, version constraints. Author a module Create, test, publish with ed25519 signing. Security & capabilities Threat model, capability sandboxing, trust boundaries.

Tooling

Tooling guide check, test, fmt, bench, debug, profile, lsp, mcp, notebook. Testing fn test_*, coverage, test runner. Production Timeouts, secrets, deploy checklist. Roadmap Where we are, where we're going, what's out of scope.

Quick reference

Syntax	What it does
`x := 1`	Bind a value (immutable)
`mut n := 0`	Mutable binding
`fn add(a, b) { a + b }`	Function (last expression returned)
`fn main -> Result { ... }`	Entry point with error handling
`expr?`	Propagate error (unwrap Ok or return Err)
`"hi $name"`	String interpolation
`x \|> f`	Pipeline
`match x { 1 { "one" } _ { "other" } }`	Pattern matching
`enum Status { Ok, Err }`	Simple enum
`enum Shape { Circle(r) }`	Sum type with payload
`map(list, fn)`	Concurrent map (fan-out by default)
`spawn(fn, args...)`	Run in background
`ch := channel(n)`	Buffered channel
`use pkg`	Import stdlib package
`use "./lib.weft" as lib`	Import local file

CLI commands

Command	What it does
`weft run file.weft`	Run a script
`weft check [--types]`	Type check
`weft test [-q]`	Run tests
`weft fmt [--check]`	Format code
`weft debug file.weft`	Debugger
`weft profile file.weft`	Profiler
`weft mcp serve file.weft`	MCP tool server
`weft lsp`	Language server
`weft update`	Self-update to latest
`weft upgrade`	Upgrade packages
`weft registry install name`	Install from registry
`weft publish --key name`	Publish to registry
`weft gen "task" -o out.weft`	Generate Weft from English
`weft doctor`	Check environment
`weft stdlib [pkg]`	List packages/members