Chaining pipes

Putting everything together, you can chain multiple operations in a single pipeline.

from pipepy import cat, grep

def my_input():
    yield "line one\n"
    yield "line two\n"
    yield "line two\n"
    yield "something else\n"
    yield "line three\n"

def my_output(stdout):
    for line in stdout:
        yield line.upper()

print(my_input() | cat | grep('line') | my_output | grep("TWO"))
# <<< LINE TWO
# ... LINE TWO

The pipeline flows as follows: 1. Generator my_input() yields lines 2. cat passes them through 3. grep('line') filters to matching lines 4. my_output transforms each line to uppercase (as a generator) 5. grep("TWO") filters again