= Mux

Package mux is a stripped-down http.ServeMux with a few select extras like
regular expression patterns and mounting.
                                                                             
- mux supports only http.HandlerFunc, http.Handler is not supported
- non-regexp handler pattern must begin with a slash "/" and must not end with
  a slash "/"
- requests with a trailing slash are redirected to the slash-less version
- mux is case-sensitive; for case-insensitive matching, look at the case-insensitive example

## Examples

+ Basic
``go
m := mux.New(http.NotFound)
m.HandleFunc("/hello", func(w http.ResponseWriter, r *http.Request) {
	io.WriteString(w, "hello")
})
http.ListenAndServe(":8080", m)
``

+ Regular expression patterns
``go
m := mux.New(http.NotFound)
m.RegexpHandleFunc(`/users/(?P<id>[0-9]+)$`, func(w http.ResponseWriter, r *http.Request) {
	id, err := strconv.Atoi(r.Context().Value("id").(string))
	if err != nil {
		w.WriteHeader(http.StatusUnprocessableEntity)
		return
	}

	fmt.Fprintf(w, "id=%d", id)

	// ...
})
``

+ Mount
``go
mu := mux.New(http.NotFound)
mu.HandleFunc("/report", func(w http.ResponseWriter, r *http.Request) {
	io.WriteString(w, "user report")
})

m := mux.New(http.NotFound)
m.Mount("/users", mu)

http.ListenAndServe(":8080", m)
``

+ Case-insensitive
``go
func caseInsensitive(handler http.HandlerFunc) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		r.URL.Path = strings.ToLower(r.URL.Path)
		handler.ServeHTTP(w, r)		
	}
}

m := mux.New(http.NotFound)
m.HandleFunc("/hello", func(w http.ResponseWriter, r *http.Request) {
	io.WriteString(w, "hello")
})

http.ListenAndServe(":8080", caseInsensitive(m))
``