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from enum import Enum, auto
from typing import Any, Callable, Generic, Iterable, TypeVar, Union
T = TypeVar("T")
def foldl(oper: Callable[[T, T], T], default: T, arr: Iterable[T]) -> T:
val = default
for x in arr:
val = oper(val, x)
return val
def contains_element_matching(cond: Callable[[T], bool], arr: Iterable[T]) -> bool:
return foldl(lambda x, y: x or y, False, map(cond, arr))
def all_matches(cond: Callable[[T], bool], arr: Iterable[T]) -> bool:
return foldl(lambda x, y: x and y, True, map(cond, arr))
Succ = TypeVar("Succ")
Err = TypeVar("Err")
class _Status(Enum):
OK = auto()
ERROR = auto()
class _ResultSentinel:
pass
_RESULT_SENTINEL = _ResultSentinel()
class Result(Generic[Succ, Err]):
@staticmethod
def ok(succ: T) -> "Result[T, Any]":
return Result(_Status.OK, succ=succ)
@staticmethod
def err(err: T) -> "Result[Any, T]":
return Result(_Status.ERROR, err=err)
def __init__(
self,
status: _Status,
succ: Union[Succ, _ResultSentinel] = _RESULT_SENTINEL,
err: Union[Err, _ResultSentinel] = _RESULT_SENTINEL,
) -> None:
super().__init__()
self._status: _Status = status
self._succ: Union[_ResultSentinel, Succ] = succ
self._err: Union[_ResultSentinel, Err] = err
def unwrap(self) -> Succ:
assert self._status is _Status.OK
assert not isinstance(self._succ, _ResultSentinel)
return self._succ
def unwrap_err(self) -> Err:
assert self._status is _Status.ERROR
assert not isinstance(self._err, _ResultSentinel)
return self._err
def is_ok(self) -> bool:
return self._status is _Status.OK
def is_err(self) -> bool:
return self._status is _Status.ERROR
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