pypes

pipes.py

import inspect
import itertools


class Pipe:
    def __init__(self, source):
        self.source = source

    def __or__(self, sink):
        if inspect.isgenerator(self.source) and not inspect.isgeneratorfunction(sink):
            result = sink(list(self.source))
        else:
            result = sink(self.source)
        return Pipe(result)


def counter():
    # Produce increasing integers
    x = 1
    while True:
        yield x
        x += 1


def every_nth(n):
    # Yield every nth item
    def consume(s):
        yield from itertools.islice(s, n - 1, None, n)

    return consume


def echo(s):
    # Print each item
    for c in s:
        print(c)
        yield c


def average(s):
    # Average of all items
    return sum(s) / len(s)


def collect(s):
    # Return all items
    return s


# Print 0-9, then their average
Pipe(range(10)) | echo | average | print

# Print a list of every other item
Pipe([1, 2, 3, 4, 5, 6]) | every_nth(2) | print

# Print multiples of 3
Pipe(counter()) | every_nth(3) | echo | collect