pipe-forward

A tiny functional composition utility for Python.

It allows you to create pipelines of functions using the | operator.

Similar to |> (pipe forward) operator in F#.

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Usage

Basic example

from pipe_forward import P  # alias for StackPipe


assert "123" @ (P(int) | float) == 123.0 # transform "123" to int, then to float
                                         # quickly interpreted as written - direct flow

# inverted flow (thumbs down)
assert float(int("123"))

Call with standard semantics

from pipe_forward import P
fn = P(int) | float
assert (P(int) | float)("123") == fn("123") == 123.0

Call with @

from pipe_forward import P
fn = P(int) | float
assert "123" @ fn == fn @ "123" == 123.0 # use prefix or suffix notation

Composability

from pipe_forward import P

# linter correctly recognizes it as P[object, int]
to_int = P(int) # convert to int

# linter correctly recognizes it as P[object, str]
to_str = to_int | str # convert to int, and then to str

assert to_int(42.0) == 42
assert to_str(42.0) == "42"

StackPipe vs LoopPipe behavior

StackPipe and LoopPipe are provided, with P as a short alias for StackPipe. They inhibit equal behavior, but implemented differently.

from pipe_forward import StackPipe
from pipe_forward import LoopPipe

stack = StackPipe(float) | str
loop = LoopPipe(float) | str

assert stack(10) == loop(10) == "10.0"

Why use this?

• Succinct function composition with | operator
• Type hint support
• Immutable
• Readable one-liners
• Explicit

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Installation

pip install git+https://github.com/phantie/pipe-forward.git -U