src/generic/arithmetic.ts

@@ -21,7 +21,21 @@ console.log($contains!(searchItem, "erwin", "tj"));
 // OK, record the type of square:
 square.reflectedType = $$typeToString!<typeof square>();
 
-type Expand<T> = T extends unknown ? { [K in keyof T]: T[K] } : never;
-type Out = Expand<Dependencies<'multiply', number>>;
+type ShallowExpand<T> =  T extends unknown ? { [K in keyof T]: T[K] } : never;
+type ExpandedParameters<T extends (...args: any) => any> = {[Index in keyof Parameters<T>]: ShallowExpand<Parameters<T>[Index]>}
+type ExpandTwice<T extends any[]> = {[Index in keyof T] : ShallowExpand<T[Index]>}
+type AsArray<T> = T extends any[] ? T : [];
+type DeepExpand<T> =
+   T extends (...args: any) => any ? (...pars: AsArray<DeepExpand<Parameters<T>>>) => DeepExpand<ReturnType<T>> :
+   T extends unknown ? { [K in keyof T]: DeepExpand<T[K]> } : never;
+type Out<T> = ShallowExpand<Dependencies<'multiply', T>>;
 
-console.log("Deps type is", $$typeToString!<Out>())
+console.log("Deps type is", $$typeToString!<<T>() => Out<T>>())
+
+type OutB = ExpandTwice<Parameters<typeof square>>;
+
+console.log("Or perhaps", $$typeToString!<OutB>())
+
+console.log("Or maybe even", $$typeToString!<
+            <T>(...args: DeepExpand<Parameters<typeof square<T>>>) => DeepExpand<ReturnType<typeof square<T>>>
+            >())