package main import ( "reflect" "github.com/kataras/iris/v12" "github.com/kataras/iris/v12/view" ) func main() { e := iris.Jet(nil, ".jet") // You can still use a file system though. e.AddFunc("greet", func(args view.JetArguments) reflect.Value { msg := "Hello, " + args.Get(0).String() + "!" return reflect.ValueOf(msg) }) err := e.ParseTemplate("program.jet", `