Elm style templating for Go

main.go

package main

import (
	"io"
	"os"
)

type Attr map[string]string

func (a Attr) writeTo(w io.Writer) error {
	for k, v := range a {
		if _, err := w.Write([]byte{' '}); err != nil {
			return err
		}
		if _, err := w.Write([]byte(k)); err != nil {
			return err
		}
		if _, err := w.Write([]byte{'=', '"'}); err != nil {
			return err
		}
		if _, err := w.Write([]byte(v)); err != nil {
			return err
		}
		if _, err := w.Write([]byte{'"'}); err != nil {
			return err
		}
	}

	return nil
}

type Node struct {
	text string
	// or
	el       string
	attr     Attr
	children []Node
}

func (n Node) writeTo(w io.Writer) error {
	if n.text != "" {
		_, err := w.Write([]byte(n.text))
		return err
	}

	w.Write([]byte{'<'})
	w.Write([]byte(n.el))
	n.attr.writeTo(w)
	w.Write([]byte{'>'})

	for _, child := range n.children {
		child.writeTo(w)
	}

	w.Write([]byte{'<', '/'})
	w.Write([]byte(n.el))
	w.Write([]byte{'>'})

	return nil
}

func h(el string, attr Attr, children []Node) Node {
	return Node{el: el, attr: attr, children: children}
}

func text(s string) Node {
	return Node{text: s}
}

func render(w io.Writer, node Node) error {
	return node.writeTo(w)
}

// so could then export
func Body(attr Attr, children []Node) Node {
	return h("body", attr, children)
}

func Div(attr Attr, children []Node) Node {
	return h("div", attr, children)
}

func H1(attr Attr, children []Node) Node {
	return h("h1", attr, children)
}

// and similar helpers for Attr if wanted

func main() {
	doc := Body(Attr{}, []Node{
		Div(Attr{"class": "box"}, []Node{
			H1(Attr{"class": "heading-big"}, []Node{
				text("Hello"),
			}),
		}),
	})

	render(os.Stdout, doc)
}