pipable 0.1.1

pseudo pipe operation in python

pipable

pseudo pipe operation in python

🔗 source code

Quick Start

Create the Pipe Object

• instantiate with the Pipe class

from pipable import Pipe

list_ = Pipe(list)
"abc" | list_    # ["a", "b", "c"]

Create Pipe Object Like Partial

• turn function into Pipe by providing argument values like using the built-in functools.partial
• preceding output will be assigned to the first argument while piping

square = Pipe(pow, exp=2)
3 | square    # 9

Note that assigning value to the first argument will raise exception, as it is preserved for the preceding output.

base2 = Pipe(pow, base=2)
3 | base2    # raise !!

Using Decorator

• transform function to Pipe factory function with the @Pipe decorator
• preceding output will be assigned to the first argument
• instantiate Pipe object like creating partial by skipping the first argument

# function with only one argument
@Pipe
def hi(name: str) -> str:
  return f"hi {name}"

"May" | hi    # "hi May"


# function with multiple arguments
@Pipe
def power(base: int, exp: int) -> int:
  return a ** b

# instantiate Pipe obj by calling without the 1st argument
2 | power(3)        # 8
2 | power(exp=3)    # 8, better be more explicit with keyword

# assign the 1st argument will cause exception
2 | power(base=3)    # raise !!

Motivation

Pipe operation is a handy feature in functional programming. It allows us to:

• write clearer and more readable code
• create less variables
• easily create new functionality by chaining the output of other functions

However it's still a missing feature in Python as of 2023. This package try to mimic pipe operation by overriding the bitwise-or operator, turn it into an infix function that take the output of previous expression as the first argument of the current function.

There are packages, such as Pipe take the similar approach. It treats pipe as iterator and work great with iterables. However, I simply want to take preceding expression as an input argument of a function then execute it. It leads to the creation of this package.

FAQ

How can I assign value to the first argument?

Assign it within a wrapper function

base2 = Pipe(lambda x: pow(2, x))
3 | base2  # 8

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Can I create open pipe?

Pipe only create closed pipe, ie. execute the function after piping with the | operator. You may consider other solutions such as:

• pipe, which create open pipe for iterators
• Coconut, a python variant that embrace functional programming

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Can I append the preceding output at the end of the argument list?

Put the preceding output at the end using a wrapper function

# prepend is the default behaviour
prepend = Pipe(print, 'b', 'c')
'a' | prepend    # 'a b c'

# use wrapper if you need append
append = Pipe(lambda x: print(1, 2, x))
3 | append    # '1 2 3'

Need Help?

Open a github issue or ping me on Twitter