example of using text/template

main.go

package main

import (
	"os"
	"text/template"
)

var peoplePage *template.Template

var peopleTemplate string = `{{range .}}
{{.FirstName}} {{.LastName}} is {{.Age}} years old.
In 10 years, {{.FirstName}} will be {{add .Age 10}}.
{{end}}`

func init() {
	peoplePage = template.Must(template.New("peopleTemplate").Funcs(template.FuncMap{
		"add": add,
	}).Parse(peopleTemplate))
}

type Person struct {
	FirstName string
	LastName  string
	Age       int
}

var people = []Person{
	{"John", "Smith", 22},
	{"Alice", "Smith", 25},
	{"Bob", "Baker", 24},
}

func main() {
	peoplePage.Execute(os.Stdout, people)
}

func add(a int, b int) int {
	return a + b
}