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Monads: Simple made Easy.
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from functools import reduce | |
class Maybe(object): | |
def __str__(self): | |
return "Maybe" | |
class Something(Maybe): | |
def __init__(self, value): | |
self.value = value | |
def __str__(self): | |
return f"Something {self.value}" | |
class Nothing(Maybe): | |
def __str__(self): | |
return "Nothing" | |
def read_and_add(prev): | |
try: | |
n = int(input("Enter a number: ")) | |
return Something(prev + n) | |
except Exception: | |
return Nothing() | |
def bind(m, f): | |
if isinstance(m, Something): | |
return f(m.value) | |
else: | |
return Nothing() | |
def unit(value): | |
return Something(value) | |
def chain(value, *functions): | |
return reduce(bind, functions, value) | |
def sum_of_3_nums(): | |
return chain( | |
unit(0), | |
read_and_add, | |
read_and_add, | |
read_and_add | |
) | |
if __name__ == '__main__': | |
r = sum_of_3_nums() | |
print(r) |
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