iterate

iterate

Iteratively apply a workflow until a termination condition is met. The workflow must return either {"result": value} to terminate or {"next": value} to continue.

Input

input:
  flow:
    steps: [ ]
    output: { }
  initial_input: <data for first iteration>
  max_iterations: 1000  # optional, prevents infinite loops

• flow (required): Complete workflow definition to execute iteratively
• initial_input (required): Input data for the first iteration
• max_iterations (optional): Maximum iterations allowed (default: 1000)

Output

output:
  result: <final result value>
  iterations: 5
  terminated: false

• result: The final result value when workflow returns {"result": value}
• iterations: Number of iterations performed
• terminated: Whether iteration was stopped by max_iterations limit

Workflow Contract

The workflow being iterated must return an object with either:

• result: Final value to return (terminates iteration)
• next: Value to pass as input to next iteration (continues)

Example

steps:
  - id: countdown
    component: /builtin/iterate
    input:
      flow:
        schema:
          type: object
          properties:
            count: { type: number }
        steps:
          - id: check_count
            component: /builtin/eval
            input:
              flow_id: { $from: { step: countdown_logic } }
              input: { $from: { workflow: input } }
        output:
          # Return "result" if count reaches 0, otherwise "next" with decremented count
          $if:
            condition: { $from: { workflow: input }, path: "count" }
            equals: 0
          then:
            result: "Countdown complete!"
          else:
            next:
              count: { $expr: "{{ input.count - 1 }}" }
      initial_input:
        count: 5
      max_iterations: 10

Use Cases

• Iterative Algorithms: Implement loops and recursive-style processing
• Convergence Testing: Run until results meet specific criteria
• State Machines: Process state transitions until final state reached
• Retry Logic: Keep trying an operation until success or max attempts