Compatibility Layer

Parslet includes a small compatibility layer so that simple Parsl and Dask workflows can be exchanged with Parslet. It provides two mechanisms:

  • Runtime shims that mimic portions of each library’s API.

  • Source-to-source converters implemented as abstract syntax tree (AST) transforms.

Note

These features are experimental and focus on pure Python code intended for local execution. Data staging directives, provider configuration and advanced Dask scheduler settings are not translated.

Dask compatibility

Drop-in replacements for dask.delayed() and dask.compute() live in parslet.compat:

from parslet.compat import delayed, compute

@delayed
def add(x, y):
    return x + y

total = compute(add(1, 2))[0]

Existing Dask scripts can be translated either programmatically or via the CLI:

from parslet.compat import convert_dask_to_parslet

rewritten = convert_dask_to_parslet(open("workflow.py").read())

parslet convert --from-dask workflow.py --to-parslet workflow_parslet.py

To move in the opposite direction:

parslet convert --from-parslet recipe.py --to-dask recipe_dask.py

Parsl compatibility

Parsl interoperability mirrors the Dask bridge. Parslet provides python_app and bash_app decorators as well as conversion utilities.

from parslet.compat import python_app

@python_app
def hello():
    return "hi"

parslet convert --from-parsl app.py --to-parslet app_parslet.py
parslet convert --from-parslet recipe.py --to-parsl recipe_parsl.py

Each exported script recreates the original DAG by rendering every node as a Parsl @python_app and wiring the dependencies.

Caveats

  • Only pure Python task bodies are handled; Bash apps and staging directives are ignored.

  • The generated code targets local execution and requires further tuning for distributed or HPC environments.

  • Always review the converted source before relying on it in production.