TYP: Inline typing annotations

.github/workflows/type_check.yml

@@ -0,0 +1,34 @@
+name: Type-check
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+  workflow_dispatch:
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.event.pull_request.number || github.sha }}
+  cancel-in-progress: true
+
+jobs:
+  type-check:
+    runs-on: ubuntu-latest
+    timeout-minutes: 5
+    steps:
+      - uses: actions/checkout@v4
+
+      - uses: astral-sh/setup-uv@v5
+        with:
+          python-version: "3.11"
+
+      - name: env setup
+        run: |
+          uv venv .venv
+          source .venv/bin/activate
+          uv pip install . numpy mypy
+
+      - name: run mypy
+        run: mypy --no-incremental --cache-dir=/dev/null .
+
+      - name: run pyright
+        uses: jakebailey/pyright-action@v2

numpy_financial/_cfinancial.pyi

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+from typing import TypeAlias
+
+import numpy as np
+import numpy.typing as npt
+
+_ArrayF64: TypeAlias = npt.NDArray[np.float64]
+
+def nper(
+    rates: _ArrayF64,
+    pmts: _ArrayF64,
+    pvs: _ArrayF64,
+    fvs: _ArrayF64,
+    whens: _ArrayF64,
+    out: _ArrayF64,
+) -> None: ...
+def npv(rates: _ArrayF64, values: _ArrayF64, out: _ArrayF64) -> None: ...