feat(mathy_pydoc): preserve Optional types in docs

Author: justindujardin

libraries/mathy_pydoc_markdown/pydocmd/loader.py

@@ -29,6 +29,7 @@
 import inspect
 import types
 from typing import Callable, Optional, List, Any
+import re
 
 function_types = (
     types.FunctionType,
@@ -40,6 +41,11 @@
 if hasattr(types, "UnboundMethodType"):
     function_types += (types.UnboundMethodType,)
 
+# Used to replace verbose type reported, e.g. "Union[str, NoneType]" with the simpler
+# form that is usually used in code "Optional[str]"
+optional_match = r"(.*)Union\[(.*),\sNoneType\](.*)"
+optional_replace = r"\1Optional[\2]\3"
+
 
 def trim(docstring):
     if not docstring:
@@ -169,6 +175,10 @@ def get_callable_placeholder(
             annotation = inspect.formatannotation(p.annotation)
         if p.default is not inspect._empty:  # type: ignore
             default_value = str(p.default)
+
+        # The type annotations expand Optional[T] to Union[T, NoneType]
+        while re.search(optional_match, annotation) is not None:
+            annotation = re.sub(optional_match, optional_replace, annotation)
         params.append(CallableArg(p.name, annotation, default_value))
 
     return_annotation = None

libraries/mathy_pydoc_markdown/testmodule/__init__.py

@@ -2,7 +2,11 @@
 
 
 def a_function_with_types(
-    inputs: List[Dict[str, Any]], auxiliary: Tuple[Optional[str]], final: int = 3
+    optional: Optional[str],
+    nested_optional: Optional[Tuple[Optional[str], Optional[int]]],
+    inputs: List[Dict[str, Any]],
+    auxiliary: Tuple[Optional[str]],
+    final: int = 3,
 ) -> List[str]:
     """Sweet typed function"""
     pass