Rustipy

Introduction

Installation

pip install rustipy

Usage

Result example

from rustipy.result import Result, Ok, Err
def square(x: int) -> int:
 return x * x
def ok_if_positive(x: int) -> Result[int, str]:
 if x > 0:
 return Ok(x)
 else:
 return Err("Not positive")
def err_to_default_ok(e: str) -> Result[int, str]:
 return Ok(DEFAULT_VALUE)
def len_str(s: str) -> int:
 return len(s)
OK_VALUE = 100
DEFAULT_VALUE = 0
def test_flatten():
 ok_ok: Result[Result[int, str], str] = Ok(Ok(OK_VALUE))
 ok_err: Result[Result[int, str], str] = Ok(Err(ERR_VALUE))
 err_outer: Result[Result[int, str], str] = Err(OTHER_ERR_VALUE)
 ok_not_result: Result[int, str] = Ok(123)
 assert ok_ok.flatten() == Ok(OK_VALUE)
 assert ok_err.flatten() == Err(ERR_VALUE)
 assert err_outer.flatten() == Err(OTHER_ERR_VALUE)
 with pytest.raises(TypeError):
 ok_not_result.flatten()
def test_chaining_err_path():
 res = (
 Ok(-5)
 .map(square)
 .and_then(ok_if_positive) # Ok(25)
 .and_then(err_if_negative) # Ok(25)
 .and_then(lambda x: Err("Force Err")) # Err("Force Err")
 .or_else(err_to_default_ok) # Ok(DEFAULT_VALUE)
 .unwrap()
 )
 assert res == DEFAULT_VALUE

Option example

from rustipy.option import Option, Some, Nothing
from tests.test_result import OK_VALUE
def int_to_some_str(x: int) -> Option[str]:
 return Some(str(x))
def int_to_nothing_if_odd(x: int) -> Option[int]:
 return Nothing if x % 2 != 0 else Some(x)
def int_to_some_str(x: int) -> Option[str]:
 return Some(str(x))
def int_to_nothing_if_odd(x: int) -> Option[int]:
 return Nothing if x % 2 != 0 else Some(x)
SOME_VALUE = 123
def test_and_then():
 some_even: Option[int] = Some(10)
 some_odd: Option[int] = Some(5)
 nothing: Option[int] = NOTHING
 assert some_even.and_then(int_to_some_str) == Some("10")
 assert some_odd.and_then(int_to_some_str) == Some("5")
 assert nothing.and_then(int_to_some_str) == NOTHING
 assert some_even.and_then(int_to_nothing_if_odd) == Some(10)
 assert some_odd.and_then(int_to_nothing_if_odd) == NOTHING
 assert nothing.and_then(int_to_nothing_if_odd) == NOTHING
def test_inspect():
 inspected_val = None
 def inspector(x: int):
 nonlocal inspected_val
 inspected_val = x * 2
 some: Option[int] = Some(SOME_VALUE)
 nothing: Option[int] = NOTHING
 assert some.inspect(inspector) is some # Returns self
 assert inspected_val == SOME_VALUE * 2
 inspected_val = None # Reset
 assert nothing.inspect(inspector) is nothing # Returns self
 assert inspected_val is None
def test_type_guards():
 some: Option[int] = Some(OK_VALUE)
 nothing: Option[int] = NOTHING
 if is_some(some):
 assert some.unwrap() == OK_VALUE
 else:
 pytest.fail("is_some failed for Some value")
 if is_nothing(some):
 pytest.fail("is_nothing succeeded for Some value")
 if is_some(nothing):
 pytest.fail("is_some succeeded for Nothing value")
 if is_nothing(nothing):
 # Can't unwrap Nothing, just check identity
 assert nothing is NOTHING
 else:
 pytest.fail("is_nothing failed for Nothing value")

Distribution Steps

$ uv build

$ git tag -vX.X.X
$ git push origin vX.X.X