IO & IOResult

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

 

retry, error recovery 등의 추가 기능을 제공하지 않는 것 같다.

차라리 Result (or ResultE) 를 사용하는 것이 나을 것 같다. 

###########################################################################
# IO
# Some IO never fails, like: getting current date and time, random number, or OS name
###########################################################################

import random

from returns.io import IO
from returns.unsafe import unsafe_perform_io

x = IO(random.randint(1, 10))
y = IO(random.choice(['A', 'B']))

z = IO.do(
    str(a) + ':' + b
    for a in x
    for b in y
)

unsafe_perform_io(z)

###########################################################################
# IOResult
# Some IO might fail, like: sending network requests, accessing filesystem, or database
###########################################################################

from returns.io import IOResult, IOResultE, IOSuccess, IOFailure

from returns.result import Result, Success
from returns.unsafe import unsafe_perform_io

x: Result[int, Exception] = Success(2)
y: Result[int, Exception] = Success(3)

io_x: IOResultE[int] = IOResult.from_result(x)
io_y: IOResultE[int] = IOResult.from_result(y)

io_success: IOResultE[int] = IOSuccess(4)
io_failure: IOResultE[int] = IOFailure(ValueError("invalid value"))

z = IOResult.do(
    a + b
    for a in io_x
    for b in io_y
)

match z:
    case IOSuccess(x):
        print(x)
    case IOFailure(e):
        print(e)

unsafe_perform_io(z)