package main

import "fmt"

type Left[A any] struct{ value A }
type Right[B any] struct{ value B }

func match[A any, B any, R any](val any, l func(A) R, r func(B) R) R {
	switch val := val.(type) {
	case Left[A]:
		return l(val.value)
	case Right[B]:
		return r(val.value)
	}
	panic("match: type error")
}

func main() {
	fmt.Println(match(Right[string]{"lol"},
		func(x string) string { return "" },
		func(x string) string { return x }))
}