Alloy (Python)

Python for logic. English for intelligence.

from alloy import command

@command(output=float)
def extract_price(text: str) -> str:
    return f"Extract the price from: {text}"

print(extract_price("This costs $49.99"))  # 49.99

Write typed AI functions that feel like normal Python. No framework, no abstractions — just functions that happen to use AI.

Install • Tutorial • Examples • Docs

Install

pip install alloy-ai                    # OpenAI only
pip install 'alloy-ai[anthropic]'       # With Anthropic
pip install 'alloy-ai[providers]'       # All providers

Quick start (OpenAI):

export OPENAI_API_KEY=sk-...
python -c "from alloy import ask; print(ask('Say hello'))"

Why Alloy?

🎯 Types you can trust: Provider‑enforced structured outputs. Get a real float, not a string to parse.

🐍 Just Python: Commands are functions. Tools are functions. Everything composes.

⚡ Production‑ready: Retries, contracts, streaming, cross‑provider support — batteries included.

🔍 Zero magic: See what’s happening. Control what’s happening. No hidden state.

Examples

Exploration with ask — Quick one‑offs and streaming

from alloy import ask

# One‑liner exploration
print(ask("List 3 reasons Alloy is useful."))

# Stream text output (text‑only streaming)
for chunk in ask.stream("Write a two‑sentence pitch for Alloy."):
    print(chunk, end="")

Typed outputs — Get back real Python objects

from dataclasses import dataclass
from alloy import command

@dataclass
class Analysis:
    sentiment: str
    score: float
    keywords: list[str]

@command(output=Analysis)
def analyze(text: str) -> str:
    return f"Analyze this text: {text}"

result = analyze("Alloy is amazing!")
print(result.score)  # 0.95

TypedDict outputs are supported too:

from typing import TypedDict
from alloy import command

class Product(TypedDict):
    name: str
    price: float

@command(output=Product)
def make() -> str:
    return "Return a Product with name='Test' and price=9.99 (numeric literal)."

print(make()["price"])  # 9.99

Tools + Contracts — Safe multi‑step workflows

from alloy import command, tool, ensure, require

@tool
@ensure(lambda x: x > 0, "Result must be positive")
def calculate(expression: str) -> float:
    return eval(expression)  # simplified example

@command(tools=[calculate])
def solve(problem: str) -> str:
    return f"Solve step by step: {problem}"

See more in examples/ and the Examples guide.

# Specific providers
pip install 'alloy-ai[anthropic]'
pip install 'alloy-ai[gemini]'
pip install 'alloy-ai[ollama]'

# Development
pip install -e '.[dev]'

export ALLOY_MODEL=gpt-5-mini
export ALLOY_TEMPERATURE=0.2
export ALLOY_MAX_TOOL_TURNS=10

from alloy import configure
configure(model="gpt-5-mini", temperature=0.2)

export ALLOY_BACKEND=fake
make examples-quick

Providers

Works with major providers — same code, zero changes:

See the full provider guide.

Next Steps

New to Alloy? → 10‑minute tutorial

Ready to build? → Browse examples

Need details? → Read the docs

Contributing

We welcome contributions! See .github/CONTRIBUTING.md.

License

MIT — see LICENSE.