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Tutorial — Level 2: Adding a Transformation

Now we insert a step that converts each character to lowercase. This introduces EACH mode — the step is called once per item.

from typing import NamedTuple
from synaflow import pipeline, step, run

class Params(NamedTuple):
    message: str

def hello(message: str) -> list[str]:
    return list(message)

def lowercase(hello: str) -> str:
    return hello.lower()

def printer(lowercase: list[str]) -> None:
    print(lowercase)

p = pipeline(
    name="tutorial",
    params=Params,
    steps=[
        step("hello", fn=hello),
        step("lowercase", fn=lowercase),
        step("printer", fn=printer),
    ],
)

run(p, Params(message="SynaFlow"))
# Output: ['s', 'y', 'n', 'a', 'f', 'l', 'o', 'w']

from typing import NamedTuple
from synaflow import pipeline, step, async_run

class Params(NamedTuple):
    message: str

async def hello(message: str) -> list[str]:
    return list(message)

async def lowercase(hello: str) -> str:
    return hello.lower()

async def printer(lowercase: list[str]) -> None:
    print(lowercase)

p = pipeline(
    name="tutorial",
    params=Params,
    steps=[
        step("hello", fn=hello),
        step("lowercase", fn=lowercase),
        step("printer", fn=printer),
    ],
)

async_run(p, Params(message="SynaFlow"))
# Output: ['s', 'y', 'n', 'a', 'f', 'l', 'o', 'w']

What happened?

  1. hello outputs list[str] — a collection of 8 characters.
  2. lowercase asks for str — a scalar. Because hello outputs an iterable and lowercase expects a scalar, SynaFlow selects EACH mode and calls lowercase once per character.
  3. EACH-mode outputs are automatically collected into a list. printer receives list[str] in ALL mode and prints it.
flowchart TD
    hello["hello<br/><i>list[str]</i>"]
    lowercase["lowercase<br/><i>ListType(str)</i>"]
    printer["printer<br/><i>None</i>"]
    message --> hello
    hello --> lowercase
    lowercase --> printer

EACH mode wraps the output type in ListType. lowercase returns str per item, so its output type is ListType(str) — meaning "a list of strings".

You can force the mode explicitly:

step("lowercase", fn=lowercase, mode=StepMode.EACH)

Next

Count the characters in Level 3.