Maybe

 

https://returns.readthedocs.io/en/latest/pages/maybe.html

(scala 의 Option 과 비슷한듯)

from returns.maybe import Maybe, Some

Maybe.from_value(1)
Maybe.from_optional(2)
Maybe.from_optional(None)

x = Some(2)
y = Some(3)
z: Maybe = Maybe.empty

# map
x.map(lambda a: a + 3)  # Some(5)

# flatMap
x.bind(lambda a: Some(a + 3))  # Some(5)

# for-comprehension
Maybe.do(
    a + b
    for a in x
    for b in y
)  # Some(5)

# pattern match
match z:
    case Some(a):
        print(a)
    case Maybe.empty:
        print('nothing')