drift-lang 0.1.0

An intent-based language for agentic systems — write agents in English, run them as async Python.

Drift

An intent-based language for agentic systems. Write your agent in English-shaped blocks, run it as async Python.

agent GrantChecker {
  model: "claude-haiku"
  budget: $0.10 per run

  step assess(application: string) -> Decision {
    let summary = summarize the application as string
    let score = score eligibility from 1 to 10 as int

    if confident<score> {
      return Decision { approved: score > 7, summary: summary }
    } else {
      escalate to human review
    }
  }
}

That's a full agent — model choice, budget, an intent verb (summarize), confidence-gated branching, structured return. The transpiler turns it into async Python that runs on Drift's thin runtime.

Install

pip install drift-lang

Optional extras:

pip install "drift-lang[mcp]"      # MCP tool support
pip install "drift-lang[dendric]"  # Dendric memory backend
pip install "drift-lang[all]"

30 seconds to your first agent

drift new hello
cd hello
drift run hello.drift --input '{"name":"Riley"}'

No API key required — Drift falls back to a mock provider so you see something work immediately. Drop an ANTHROPIC_API_KEY or OPENAI_API_KEY into .env to use a real model.

CLI

drift new <name>          Scaffold a starter project
drift run <file.drift>    Transpile and execute
drift check <file.drift>  Validate syntax
drift transpile <file>    Emit Python (use -o to write to a file)
drift lex / parse         Debug tooling

What's in the language

• agent — top-level unit. Has model, budget, state, memory, and steps.
• step — typed sub-procedure. Body is a sequence of declarative statements.
• Intent verbs — summarize, extract, classify, translate, match, generate, etc. Each one becomes a typed LLM call.
• confident<T> — confidence-gated branching. Run the cheap path when sure, escalate when not.
• model { … } — multi-provider routing with prefer, fallback, upgrade when confidence < 0.7, and stream "fast" then "slow".
• tool name from python|mcp|rest — declare external tools. MCP runs against the official SDK.
• pipeline — composable flow with ->, =>, ~>, |> operators.
• for each x in xs parallel — asyncio.gather underneath.
• attempt / recover — structured error handling with retry, fail, and named arms.
• memory — short-term scratchpad or durable backend (Dendric). remember, recall, deja_vu, forget.
• define verb — extend the intent vocabulary with your own typed verbs.
• Cross-agent calls — OtherAgent.step(args) just works.

Docs

File	For
LLM.md	Coding agents (Claude, Cursor, Copilot) — complete reference for one-shot loading
docs/language.md	Humans learning Drift
docs/cookbook.md	Copy-paste patterns
docs/gotchas.md	Common mistakes

Examples

See examples/ for working .drift programs and their generated Python:

• hello.drift — minimal agent
• confident_demo.drift — confident<T> branching
• grant_checker.drift — end-to-end intent + structured return
• inbox_sorter.drift — for each … parallel triage
• grant_checker_with_memory.drift — Dendric-backed long-term memory

Status

Alpha — language surface is stable, runtime works, 344/344 tests passing. Voice primitives parse but adapters aren't wired yet. Type system beyond confident<T> is on the roadmap.

License

MIT