mirror of
https://github.com/correl/typesafe-monads.git
synced 2024-11-14 19:19:32 +00:00
76 lines
1.9 KiB
Python
76 lines
1.9 KiB
Python
import pytest # type: ignore
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from typing import Callable, List
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from monads.maybe import Maybe, Just, Nothing, maybe, first, last
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def test_bind_just() -> None:
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m: Maybe[int] = Just(5)
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increment: Callable[[int], Maybe[int]] = lambda x: Just(x + 1)
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assert Just(6) == m.bind(increment)
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def test_bind_nothing() -> None:
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m: Maybe[int] = Nothing()
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increment: Callable[[int], Maybe[int]] = lambda x: Just(x + 1)
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assert Nothing() == m.bind(increment)
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def test_apply_just_to_just() -> None:
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m: Maybe[int] = Just(5)
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increment: Callable[[int], int] = lambda x: x + 1
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assert Just(6) == m.apply(Maybe.pure(increment))
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def test_apply_just_to_nothing() -> None:
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m: Maybe[int] = Nothing()
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increment: Callable[[int], int] = lambda x: x + 1
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assert Nothing() == m.apply(Maybe.pure(increment))
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def test_apply_nothing_to_just() -> None:
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m: Maybe[int] = Just(5)
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f: Maybe[Callable[[int], int]] = Nothing()
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assert Nothing() == m.apply(f)
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def test_apply_nothing_to_nothing() -> None:
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m: Maybe[int] = Nothing()
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f: Maybe[Callable[[int], int]] = Nothing()
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assert Nothing() == m.apply(f)
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def test_just_withdefault() -> None:
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m: Maybe[int] = Just(5)
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assert 5 == m.withDefault(0)
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def test_nothing_withdefault() -> None:
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m: Maybe[int] = Nothing()
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assert 0 == m.withDefault(0)
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def test_maybe_none() -> None:
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assert isinstance(maybe(None), Nothing)
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def test_maybe_something() -> None:
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assert isinstance(maybe(False), Just)
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def test_maybe_boolean_false() -> None:
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assert isinstance(maybe(False, predicate=bool), Nothing)
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def test_maybe_boolean_true() -> None:
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assert isinstance(maybe(True, predicate=bool), Just)
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def test_first() -> None:
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maybes: List[Maybe[int]] = [Nothing(), Just(1), Just(2)]
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assert Just(1) == first(maybes)
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def test_last() -> None:
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maybes: List[Maybe[int]] = [Just(1), Just(2), Nothing()]
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assert Just(2) == last(maybes)
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