Map async (#165)

Continuation of #162

Author: francium

CHANGELOG.md

@@ -13,8 +13,8 @@ Possible log types:
 
 ## [Unreleased]
 
+- `[added]` Add `map_async` for async functions (#165)
 - `[fixed]` Add `do_async()` to handle edge case in `do()` involving multiple inlined awaits (#149)
-
 - `[added]` Add support for Python 3.12 (#157)
 
 ## [0.15.0] - 2023-12-04

src/result/result.py

@@ -151,6 +151,15 @@ def map(self, op: Callable[[T], U]) -> Ok[U]:
         """
         return Ok(op(self._value))
 
+    async def map_async(
+        self, op: Callable[[T], Awaitable[U]]
+    ) -> Ok[U]:
+        """
+        The contained result is `Ok`, so return the result of `op` with the
+        original value passed in
+        """
+        return Ok(await op(self._value))
+
     def map_or(self, default: object, op: Callable[[T], U]) -> U:
         """
         The contained result is `Ok`, so return the original value mapped to a new
@@ -340,6 +349,13 @@ def map(self, op: object) -> Err[E]:
         """
         return self
 
+    async def map_async(self, op: object) -> Err[E]:
+        """
+        The contained result is `Ok`, so return the result of `op` with the
+        original value passed in
+        """
+        return self
+
     def map_or(self, default: U, op: object) -> U:
         """
         Return the default value

tests/test_result.py

@@ -225,6 +225,25 @@ async def test_and_then_async() -> None:
     ).err() == 3
 
 
+@pytest.mark.asyncio
+async def test_map_async() -> None:
+    async def str_upper_async(s: str) -> str:
+        return s.upper()
+
+    async def str_async(x: int) -> str:
+        return str(x)
+
+    o = Ok('yay')
+    n = Err('nay')
+    assert (await o.map_async(str_upper_async)).ok() == 'YAY'
+    assert (await n.map_async(str_upper_async)).err() == 'nay'
+
+    num = Ok(3)
+    errnum = Err(2)
+    assert (await num.map_async(str_async)).ok() == '3'
+    assert (await errnum.map_async(str_async)).err() == 2
+
+
 def test_or_else() -> None:
     assert Ok(2).or_else(sq).or_else(sq).ok() == 2
     assert Ok(2).or_else(to_err).or_else(sq).ok() == 2