Add sugar for the params

Author: msullivan

spec-draft.rst

@@ -24,10 +24,18 @@ Extended Callables, take 2
 
 We introduce a ``Param`` type the contains all the information about a function param::
 
-  class Param[N: str | None, T, Q: ParamQuals = typing.Never]:
-      pass
+    class Param[N: str | None, T, Q: ParamQuals = typing.Never]:
+        pass
+
+    ParamQuals = typing.Literal["*", "**", "default", "keyword"]
 
-  ParamQuals = typing.Literal["*", "**", "default", "keyword"]
+    type PosParam[T] = Param[Literal[None], T]
+    type PosDefaultParam[T] = Param[Literal[None], T, Literal["default"]]
+    type DefaultParam[N: str, T] = Param[N, T, Literal["default"]]
+    type NamedParam[N: str, T] = Param[N, T, Literal["keyword"]]
+    type NamedDefaultParam[N: str, T] = Param[N, T, Literal["keyword", "default"]]
+    type ArgsParam[T] = Param[Literal[None], T, Literal["*"]]
+    type KwargsParam[T] = Param[Literal[None], T, Literal["**"]]
 
 And then, we can represent the type of a function like::
 
@@ -59,6 +67,21 @@ as (we are omiting the ``Literal`` in places)::
     ]
 
 
+or, using the type abbreviations we provide::
+
+    Callable[
+        [
+            PosParam[int],
+            Param["b", int],
+            DefaultParam["c", int,
+            ArgsParam[int, "*"],
+            NamedParam["d", int],
+            NamedDefaultParam["e", int],
+            KwargsParam[int],
+        ],
+        int,
+    ]
+
 Rationale
 '''''''''
 We need extended callable support, in order to inspect and produce callables via type-level computation. mypy supports `extended callables <https://mypy.readthedocs.io/en/stable/additional_features.html#extended-callable-types>`__ but they are deprecated in favor of callback protocols.

tests/test_schemalike.py

@@ -10,6 +10,7 @@
     GetType,
     GetName,
     Member,
+    NamedParam,
     Param,
     StrConcat,
 )
@@ -49,7 +50,7 @@ class Property:
             Callable[
                 [
                     Param[Literal["self"], Schemaify[T]],
-                    Param[Literal["schema"], Schema, Literal["keyword"]],
+                    NamedParam[Literal["schema"], Schema, Literal["keyword"]],
                 ],
                 GetType[p],
             ],

typemap/typing.py

@@ -1,5 +1,6 @@
 import contextvars
 import typing
+from typing import Literal
 from typing import _GenericAlias  # type: ignore
 
 _SpecialForm: typing.Any = typing._SpecialForm
@@ -74,7 +75,7 @@ class DropAnnotations[T]:
 ###
 
 
-MemberQuals = typing.Literal["ClassVar", "Final"]
+MemberQuals = Literal["ClassVar", "Final"]
 
 
 class Member[
@@ -91,7 +92,7 @@ class Member[
     definer: D
 
 
-ParamQuals = typing.Literal["*", "**", "="]
+ParamQuals = Literal["*", "**", "keyword", "default"]
 
 
 class Param[N: str | None, T, Q: ParamQuals = typing.Never]:
@@ -100,11 +101,20 @@ class Param[N: str | None, T, Q: ParamQuals = typing.Never]:
     quals: Q
 
 
-type GetName[T: Member | Param] = GetAttr[T, typing.Literal["name"]]
-type GetType[T: Member | Param] = GetAttr[T, typing.Literal["typ"]]
-type GetQuals[T: Member | Param] = GetAttr[T, typing.Literal["quals"]]
-type GetInit[T: Member] = GetAttr[T, typing.Literal["init"]]
-type GetDefiner[T: Member] = GetAttr[T, typing.Literal["definer"]]
+type PosParam[T] = Param[Literal[None], T]
+type PosDefaultParam[T] = Param[Literal[None], T, Literal["default"]]
+type DefaultParam[N: str, T] = Param[N, T, Literal["default"]]
+type NamedParam[N: str, T] = Param[N, T, Literal["keyword"]]
+type NamedDefaultParam[N: str, T] = Param[N, T, Literal["keyword", "default"]]
+type ArgsParam[T] = Param[Literal[None], T, Literal["*"]]
+type KwargsParam[T] = Param[Literal[None], T, Literal["**"]]
+
+
+type GetName[T: Member | Param] = GetAttr[T, Literal["name"]]
+type GetType[T: Member | Param] = GetAttr[T, Literal["typ"]]
+type GetQuals[T: Member | Param] = GetAttr[T, Literal["quals"]]
+type GetInit[T: Member] = GetAttr[T, Literal["init"]]
+type GetDefiner[T: Member] = GetAttr[T, Literal["definer"]]
 
 
 class Attrs[T]: