A rough idea of a web app framework in Go

webapp.go

package webapp

import (
	"fmt"
	"net/http"
)

type Error struct {
	code int
}

func (e Error) Error() string { return "" }

func fail(w http.ResponseWriter, err Error) {}

type HandlerFunc func(http.ResponseWriter, *http.Request) error

func (fn HandlerFunc) ServeHTTP(w http.ResponseWriter, r *http.Request) {
	if err := fn(w, r); err != nil {
		if ierr, ok := err.(Error); ok {
			fail(w, ierr)
		} else {
			e := Error{code: http.StatusInternalServerError}
			fail(w, e)
		}
	}
}

func get(fn HandlerFunc) HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) error {
		if r.Method != "GET" {
			return fmt.Errorf("NotFound")
		}
		return fn(w, r)
	}
}

func sayhello(w http.ResponseWriter, r *http.Request) error {
	fmt.Fprintln(w, "Hi!")
	return nil
}

func main() {
	mux := http.NewServeMux()
	mux.Handle("/hello", get(sayhello))
	http.ListenAndServe(":8080", mux)
}