Functional Python

fn.py

import time

def tail(f, from_start=False):
    try:
        if from_start:
            f.seek(0, 2) # go to the end of file

        while True:
            line = f.readline()
            if not line:
                time.sleep(0.1)
                continue
            yield line
    except KeyboardInterrupt:
        pass
    except Exception as ex:
        raise ex

def uniq(iterable, key=lambda x: x):
    previous = set()
    for v, k in ((elem, key(elem)) for elem in iterable):
        if k not in previous:
            yield v
            previous.add(k)

def ireduce(func, iterable, initializer=None):
    it = iter(iterable)
    value = next(it) if initializer is None else initializer
    for element in it:
        value = func(value, element)
        yield value

def _fold(func, iterable, iterize):
    it = iterize(iterable)
    value = next(it)
    yield value
    for i in it:
        value = func(value, i)
        yield value

def foldl(func, iterable):
    for i in _fold(func, iterable, iter):
        yield i

def foldr(func, iterable):
    for i in _fold(func, iterable, reversed):
        yield i