dpk / functionkit

(Eventually) a potpourri of functional programming-related tools for Python

functionkit

A potpourri of functional programming tools for Python 3. Not much here right now, but there will be soon I hope!

functionkit.strict

When you want to make a lazy generator in Python, it's easy:

def fizzbuzz(input):
    for n in input:
        if n % 3 == 0 and n % 5 == 0:
            yield 'fizzbuzz'
        elif n % 3 == 0:
            yield 'fizz'
        elif n % 5 == 0:
            yield 'buzz'
        else:
            yield n

but if you want to make the function return a strict list that can be indexed immediately, or just passed to another function like reversed that can't deal with lazy iterators, you typically have to transform it completely to something like this:

def fizzbuzz(input):
    result = []
    for n in input:
        if n % 3 == 0 and n % 5 == 0:
            result.append('fizzbuzz')
        elif n % 3 == 0:
            result.append('fizz')
        elif n % 5 == 0:
            result.append('buzz')
        else:
            result.append(n)
    
    return result

i.e. explicitly mutating the list. This is not very nice.

functionkit.strict provides the decorators listify, setify, and dictify which convert the values from a generator to a list, set, or dict respectively. These are all based on the more primitive strictify so you can produce results of any kind, like a collection.deque for fast appends to either end of the result list.

@listify
def one_two_three():
    yield 1
    yield 2
    yield 3

one_two_three() #=> [1, 2, 3]

@dictify
def animals():
    # yield two-tuples
    yield ('tiger', 'panthera tigris')
    yield ('kiwi', 'apteryx haastii')
    yield ('goldfish', 'carassius auratus')

animals() #=> {'tiger': 'panthera tigris', 'kiwi': 'apteryx haastii', 'goldfish': 'carassius auratus'}

@strictify(collections.deque)
def planets():
    yield 'earth'
    yield 'mars'
    yield 'jupiter'

solar_system = planets()
solar_system.append('uranus')
solar_system.appendleft('venus')
solar_system #=> deque(['venus', 'earth', 'mars', 'jupiter', 'uranus'])

Note these will all diverge and run out of memory if you generate an infinite stream with them!