feat: Enable typehints in pre-commit and add typehints to readxml

.pre-commit-config.yaml

@@ -59,6 +59,13 @@ repos:
     - id: flake8
       args: ["--count", "--statistics"]
 
+-   repo: https://github.com/pre-commit/mirrors-mypy
+    rev: v0.971
+    hooks:
+      - id: mypy
+        files: src
+        args: []
+
 -   repo: https://github.com/nbQA-dev/nbQA
     rev: 1.4.0
     hooks:

pyproject.toml

@@ -96,3 +96,55 @@ pyupgrade = 1
 
 [tool.nbqa.addopts]
 pyupgrade = ["--py37-plus"]
+
+[tool.mypy]
+files = "src"
+python_version = "3.10"
+warn_unused_configs = true
+strict = true
+show_error_codes = true
+enable_error_code = ["ignore-without-code", "redundant-expr", "truthy-bool"]
+warn_unreachable = true
+
+[[tool.mypy.overrides]]
+module = [
+  'matplotlib.*',
+  'jax.*',
+  'click.*',
+  'click_completion.*',
+  'numpy.*',
+  'scipy.*',
+  'jsonpatch.*',
+  'uproot.*',
+  'yaml.*',
+  'jsonschema.*',
+  'tqdm.*',
+]
+ignore_missing_imports = true
+
+[[tool.mypy.overrides]]
+module = [
+  'pyhf',
+  'pyhf.tensor.*',
+  'pyhf.optimize.*',
+  'pyhf.contrib.*',
+  'pyhf.infer.*',
+  'pyhf.interpolators.*',
+  'pyhf.cli.*',
+  'pyhf.modifiers.*',
+  'pyhf.exceptions.*',
+  'pyhf.parameters.*',
+  'pyhf.schema.*',
+  'pyhf.writexml',
+  'pyhf.workspace',
+  'pyhf.patchset',
+  'pyhf.compat',
+  'pyhf.events',
+  'pyhf.utils',
+  'pyhf.mixins',
+  'pyhf.constraints',
+  'pyhf.pdf',
+  'pyhf.simplemodels',
+  'pyhf.probability',
+]
+ignore_errors = true

setup.cfg

@@ -42,6 +42,7 @@ install_requires =
     jsonpatch>=1.15
     pyyaml>=5.1  # for parsing CLI equal-delimited options
     importlib_resources>=1.3.0; python_version < "3.9"  # for resources in schema
+    typing_extensions; python_version == "3.7"  # for TypedDict, Literal
 
 [options.packages.find]
 where = src