Loop Iterative Accumulation

Demonstrates loop iterations carrying forward output from previous iterations.

Each iteration receives the previous iteration's output via step_input.get_last_step_content(), enabling iterative processing patterns like accumulation, refinement, and convergence.

This example increments a numeric value by 10 each iteration, stopping when it reaches 50 or more.

1from kern.workflow import Loop, Step, Workflow
2from kern.workflow.types import StepInput, StepOutput
3
4
5def increment_executor(step_input: StepInput) -> StepOutput:
6    """Increment the previous step's numeric content by 10."""
7    last_content = step_input.get_last_step_content()
8    if last_content and last_content.isdigit():
9        new_value = int(last_content) + 10
10        return StepOutput(content=str(new_value))
11    return StepOutput(content="0")
12
13
14workflow = Workflow(
15    name="Iterative Accumulation Workflow",
16    steps=[
17        Step(
18            name="Initial Value",
19            executor=lambda step_input: StepOutput(content=step_input.input),
20        ),
21        Loop(
22            name="Increment Loop",
23            steps=[
24                Step(
25                    name="Increment Step",
26                    executor=increment_executor,
27                )
28            ],
29            end_condition=lambda step_outputs: int(step_outputs[-1].content) >= 50,
30            max_iterations=10,
31            forward_iteration_output=True,  # Default: each iteration gets previous output
32        ),
33    ],
34)
35
36if __name__ == "__main__":
37    # Starting from 35: iteration 1 -> 45, iteration 2 -> 55 (>= 50, stops)
38    workflow.print_response("35")