Hello World

Alpha (v0.1). Breaking changes expected.

Create a file called hello.keel:

agent Hello {
  @role "A friendly greeter"

  @on_start {
    Schedule.every(5.seconds, () => {
      Io.notify("Hello from Keel!")
    })
  }
}

run(Hello)

Run it:

KEEL_OLLAMA_MODEL=gemma4 keel run hello.keel

Output:

⚡ LLM provider: Ollama (http://localhost:11434)
▸ Starting agent Hello
  role: A friendly greeter
  model: gemma4 (ollama @ http://localhost:11434)

  ⏱ Schedule.every(5.seconds)
  ▸ Hello from Keel!

  ▸ Agent running. Press Ctrl+C to stop.
  ▸ Hello from Keel!
  ▸ Hello from Keel!

Press Ctrl+C to stop.

What just happened?

1. agent Hello — declares an agent.
2. @role "..." — an attribute describing what the agent does. Bound to the LLM provider for any Ai.* calls.
3. @model "..." — which model to use.
4. @on_start { ... } — a lifecycle hook that runs when the agent starts.
5. Schedule.every(5.seconds, () => { ... }) — schedules a recurring block. Schedule is a stdlib namespace, always in scope.
6. Io.notify(...) — prints to the terminal. Io is also stdlib.
7. run(Hello) — starts the agent.

No imports. The Schedule, Io, Ai namespaces are in scope from the start — that’s the prelude.

Using AI

type Mood = happy | neutral | sad

task analyze(text: str) -> Mood {
  Ai.classify(text, as: Mood) ?? Mood.neutral
}

agent MoodBot {
  @role "Analyzes the mood of text"

  @on_start {
    Schedule.every(10.seconds, () => {
      mood = analyze("I love building programming languages!")
      Io.notify("Mood: {mood}")
    })
  }
}

run(MoodBot)

Ai.classify sends the text to the LLM and parses the response into one of the enum variants. ?? supplies a default when the LLM is unavailable or the response doesn’t match.

Next: Your First Agent →