asdf

mod.ts

@@ -1,16 +1,27 @@
 type Ufcs<C extends {"prototype": any}> = {
     [K in keyof C["prototype"]]:
-        (_this: C) => C["prototype"][K]
-} & { new (): C }
+        C["prototype"][K] extends (...args: any[]) => any
+            ? (...args: Parameters<C["prototype"][K]>) => (_this: C) => ReturnType<C["prototype"][K]>
+            : never
+} & C
 
-const ufcs = <C extends {"prototype": any}>(_class: C) => {
+export const ufcs = <C extends {"prototype": unknown}>(_class: C) => {
     Object.getOwnPropertyNames(_class.prototype)
         .forEach(prop => {
-            if (prop != "prototype") {
+            if (prop != "constructor") {
                 Object.defineProperty(_class, prop, {
-                    value: (_this: any) => _this[prop]()
+                    value: (...args: unknown[]) => (_this: any) => _this[prop](...args)
                 })
             }
         })
     return _class as unknown as Ufcs<C>
-}
+}
+
+const Duck = ufcs(class Duck {
+    quack(num: number) {
+        console.log("Quack!", num)
+    }
+})
+const duck = new Duck
+Duck.quack(123)(duck); // Quack! 123
+duck.quack(123) // Quack! 123

test.ts

@@ -0,0 +1,8 @@
+import { ufcs } from "./mod.ts"
+
+const Duck = ufcs(class Duck {
+    quack() {
+        console.log("Quack!")
+    }
+})
+Duck.quack(new Duck) // Quack!