Duck Typing (horror) in Go

duck.go

package main

import "fmt"

type Duck interface {
	Swim()
	Quack()
}

type Mallard struct{}

func (m Mallard) Swim() { fmt.Println("mallard swimming") }

func (m Mallard) Quack() { fmt.Println("mallard quacking") }

type Dog struct{}

func (d Dog) Swim() { fmt.Println("dog swimming") }

func (d Dog) Bark() { fmt.Println("woof") }

func quack(ducks ...any) {
	for _, duck := range ducks {
		duck.(interface { Swim() }).Swim()
		duck.(interface { Quack() }).Quack()
	}
}

func main() {
	quack(Mallard{}, Dog{})
}

From https://www.ccampo.me/go/2024/08/20/go-duck-typing.html

Also https://go.dev/play/p/hi8vEivq29H