Created
August 17, 2017 09:23
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compose functions in python like haskell
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class Composable(object): | |
''' A function decorator that allows you to use Haskell style dot notation for function composition ''' | |
fns = {} | |
def __init__(self, fn): | |
self.fn = fn | |
Composable.fns[fn.__name__] = fn | |
def __call__(self, *args, **kwargs): | |
''' simply calls the function ''' | |
return self.fn(*args, **kwargs) | |
def __getattr__(self, other): | |
''' The returned function will only be able to be on the left of a composition, for now ''' | |
return Composable(compose(self.fn, self.fns[other])) | |
# Examples: | |
@Composable | |
def add_17(x): | |
return x + 17 | |
@Composable | |
def subtract_7(x): | |
return x - 17 | |
add_17 . subtract_7 (10) == 20 # True | |
Composable(lambda x: x * 2) . add_17 . add_17 . subtract_7 == 54 # True | |
# Limitations | |
# - Anonymous functions can only be on the left hand side of a composition (because they don't have names) | |
# Ideas: | |
# - Get the module name and scope when creating a Composable | |
# - This will allow you to have a function with the same name from two different modules | |
# - It will also allow you to lookup unknown functions in the module it is being called from |
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Where is 'compose' function then?