"""
Result type for handling success/error cases
"""
from typing import TypeVar, Generic, Optional, Callable
from dataclasses import dataclass

T = TypeVar('T')
E = TypeVar('E')


@dataclass
class Success(Generic[T]):
    """Successful result with value"""
    value: T

    def is_success(self) -> bool:
        return True

    def is_error(self) -> bool:
        return False

    def map(self, func: Callable[[T], 'Success']) -> 'Success[T]':
        """Apply function to value"""
        return func(self.value)


@dataclass
class Error(Generic[E]):
    """Error result with error value"""
    error: E

    def is_success(self) -> bool:
        return False

    def is_error(self) -> bool:
        return True

    def map(self, func: Callable) -> 'Error[E]':
        """Return self on error"""
        return self


Result = Success[T] | Error[E]