Add result.bind_with helper function

expression/core/result.py

@@ -20,6 +20,8 @@
     Literal,
     TypeGuard,
     TypeVar,
+    ParamSpec,
+    Concatenate,
     cast,
     get_args,
     get_origin,
@@ -44,6 +46,7 @@
 _TResult = TypeVar("_TResult")
 _TError = TypeVar("_TError")
 _TErrorOut = TypeVar("_TErrorOut", covariant=True)
+_TParams = ParamSpec("_TParams")
 
 
 @tagged_union(frozen=True, order=True)
@@ -415,6 +418,14 @@ def bind(
     return result.bind(mapper)
 
 
+def bind_with(
+    mapper: Callable[Concatenate[_TSource, _TParams], Result[_TResult, Any]],
+    *args: _TParams.args,
+    **kwargs: _TParams.kwargs,
+) -> Callable[[Result[_TSource, _TError]], Result[_TResult, _TError]]:
+    return bind(curry_flip(1)(mapper)(*args, **kwargs))
+
+
 def dict(source: Result[_TSource, _TError]) -> builtins.dict[str, _TSource | _TError | Literal["ok", "error"]]:
     return source.dict()
 
@@ -492,6 +503,7 @@ def of_option_with(value: Option[_TSource], error: Callable[[], _TError]) -> Res
     "Ok",
     "Result",
     "bind",
+    "bind_with",
     "default_value",
     "default_with",
     "dict",

tests/test_result.py

@@ -215,6 +215,28 @@ def test_result_bind_piped(x: int, y: int):
             assert False
 
 
+@given(st.integers(), st.integers())  # type: ignore
+def test_result_bind_with_piped(x: int, y: int):
+    xs: Result[int, str] = Ok(x)
+
+    def mapper(x: int, y: int) -> Result[int, str]:
+        return Ok(x - y)
+
+    ys = xs.pipe(result.bind_with(mapper, y=y))
+    match ys:
+        case Result(tag="ok", ok=value):
+            assert Ok(value) == mapper(x, y=y)
+        case _:
+            assert False
+
+    ys = xs.pipe(result.bind_with(mapper, y))
+    match ys:
+        case Result(tag="ok", ok=value):
+            assert Ok(value) == mapper(x, y)
+        case _:
+            assert False
+
+
 @given(st.lists(st.integers()))  # type: ignore
 def test_result_traverse_ok(xs: list[int]):
     ys: Block[Result[int, str]] = Block([Ok(x) for x in xs])