package main

type Iterator[T any] interface {
	Iterate()
}

type IteratorFunc[T any] func(fn func(T) bool)

func (f IteratorFunc[T]) Iterate() {
}

func FromIterator[T any](it Iterator[T]) {
	it.Iterate()
}

func Foo[T, R any]() {
	FromIterator[R](IteratorFunc[R](nil))
}

func main() {
	Foo[int, int]()

	f(fn)
}

type Stream[T any] struct {
	it Iterator[T]
}

func (s Stream[T]) Iterate(fn func(T) bool) {
	if s.it == nil {
		return
	}
	s.it.Iterate(fn)
}

func FromIterator[T any](it Iterator[T]) Stream[T] {
	return Stream[T]{it: it}
}

func (s Stream[T]) DropWhile(fn func(T) bool) Stream[T] {
	return Pipe[T, T](s, func(t T) (T, bool) {
		return t, true
	})
}