refactor: Simplify backoff.constant wait generator implementation

CHANGELOG.md

@@ -22,6 +22,8 @@
 
 - Check types with [`ty`](https://docs.astral.sh/ty/) and update some type annotations [#179](https://github.com/python-backoff/backoff/pull/179)
 
+- Simplify `backoff.constant` wait generator implementation [#180](https://github.com/python-backoff/backoff/pull/180)
+
 ## [v2.3.1] - 2025-12-18
 
 ### Fixed

backoff/_typing.py

@@ -41,4 +41,4 @@ class Details(_Details, total=False):
 _MaybeLogger = Union[str, logging.Logger, logging.LoggerAdapter, None]
 _MaybeSequence = Union[T, Sequence[T]]
 _Predicate = Union[Callable[[T], bool], Callable[[T], Coroutine[Any, Any, bool]]]
-_WaitGenerator = Callable[..., Generator[Union[float, None], None, None]]
+_WaitGenerator = Callable[..., Generator[Union[float, None], Union[int, None], None]]

backoff/_wait_gen.py

@@ -84,8 +84,8 @@ def fibo(max_value: int | None = None) -> Generator[int | None, None, None]:
 
 
 def constant(
-    interval: int | Iterable[float] = 1,
-) -> Generator[int | float | None, None, None]:
+    interval: float | Iterable[float] = 1,
+) -> Generator[int | float | None, int | None, None]:
     """Generator for constant intervals.
 
     Args:
@@ -94,19 +94,20 @@ def constant(
     # Advance past initial .send() call
     yield  # type: ignore[misc]
 
-    try:
-        itr = iter(interval)  # type: ignore
-    except TypeError:
-        itr = itertools.repeat(interval)  # type: ignore[arg-type]
+    itr = (
+        itertools.repeat(interval)
+        if isinstance(interval, (int, float))
+        else iter(interval)
+    )
 
     for val in itr:
-        yield val  # ty:ignore[invalid-yield]
+        yield val
 
 
 def runtime(
     *,
     value: Callable[[Any], float],
-) -> Generator[float | None, None, None]:
+) -> Generator[float | None, int | None, None]:
     """Generator that is based on parsing the return value or thrown
         exception of the decorated method
 

pyproject.toml

@@ -63,7 +63,6 @@ typing = [
     { include-group = "test" },
     "mypy>=0.942",
     "ty>=0.0.59",
-    "types-requests>=2.27.20",
 ]
 
 [tool.hatch.build.targets.sdist]
@@ -202,6 +201,12 @@ ignore = [
   "UP028",
 ]
 
+[tool.mypy]
+follow_untyped_imports = true
+warn_unreachable = true
+warn_unused_configs = true
+warn_unused_ignores = true
+
 [tool.ruff.lint.per-file-ignores]
 "**/doccmd_*.py" = [
   "F811",  # redefinition of unused

tests/test_wait_gen.py

@@ -97,9 +97,16 @@ def test_constant():
     for _i in range(9):
         assert next(gen) == 3
 
+    gen = backoff.constant(interval=[1, 2.0, 3.25])
+    gen.send(None)
+    assert next(gen) == 1
+    assert next(gen) == 2.0
+    assert next(gen) == 3.25
+    assert next(gen, None) is None
+
 
 def test_runtime():
     gen = backoff.runtime(value=lambda x: x)
     gen.send(None)
     for i in range(20):
-        assert i == gen.send(i)  # ty:ignore[invalid-argument-type]
+        assert i == gen.send(i)