Golang: Create a Acyclic function graph

acyclic.go

package main

import (
	"fmt"
)

// Data that flows through the processing pipeline
type Data struct {
	Type string
	Data string
}

// The Handler function processes the data and then
// call the handlers downstream from itself
// Each downstream function gets its own copy of the data
type Handler func(Data) error

type HandlerChain interface {
	Chain([]Handler) Handler
}

type Node struct {
	Name string
}

func (n *Node) Chain(h ...Handler) Handler {
	return func(d Data) error {
		downstreamHandlers := h
		d.Data = d.Data + "->" + n.Name

		for _, f := range downstreamHandlers {
			if f == nil {
				fmt.Println(d.Data)
				return nil
			}
			if err := f(d); err != nil {
				return err
			}
		}
		return nil
	}
}

func main() {
	a := Node{"A"}
	b := Node{"B"}
	c := Node{"C"}
	d := Node{"D"}
	e := Node{"E"}
	f := Node{"F"}

	path1 := b.Chain(c.Chain(nil))
	path2 := d.Chain(d.Chain(e.Chain(nil)))
	path3 := f.Chain(path1, path2)

	tree := a.Chain(path1, path2, path3)

	tree(Data{Data: "hello"})
}