diff --git a/src/study/day9Interface/HttpHandler.go b/src/study/day9Interface/HttpHandler.go
new file mode 100644
index 0000000..bc20aa6
--- /dev/null
+++ b/src/study/day9Interface/HttpHandler.go
@@ -0,0 +1,64 @@
+package main
+
+import (
+	"fmt"
+	"net/http"
+)
+
+type dollars float32
+
+func (d dollars) String() string {
+	return fmt.Sprintf("$%.2f", d)
+}
+
+type database map[string]dollars
+
+func (db database) ServeHTTP(w http.ResponseWriter, req *http.Request) {
+	switch req.URL.Path {
+	case "/list":
+		for item, price := range db {
+			fmt.Fprintf(w, "%s: %s\n", item, price)
+		}
+	case "/price":
+		item := req.URL.Query().Get("item")
+		price, ok := db[item]
+		if !ok {
+			w.WriteHeader(http.StatusNotFound) // 404
+			fmt.Fprintf(w, "no such item: %q\n", item)
+			return
+		}
+		fmt.Fprintf(w, "%s\n", price)
+	default:
+		w.WriteHeader(http.StatusNotFound) // 404
+		fmt.Fprintf(w, "no such page: %s\n", req.URL)
+	}
+}
+
+func (db database) list(w http.ResponseWriter, req *http.Request) {
+	for item, price := range db {
+		fmt.Fprintf(w, "%s: %s\n", item, price)
+	}
+}
+
+func (db database) price(w http.ResponseWriter, req *http.Request) {
+	item := req.URL.Query().Get("item")
+	price, ok := db[item]
+	if !ok {
+		w.WriteHeader(http.StatusNotFound) // 404
+		fmt.Fprintf(w, "no such item: %q\n", item)
+		return
+	}
+	fmt.Fprintf(w, "%s\n", price)
+
+}
+func main() {
+	db := database{"shoes": 50, "socks": 5}
+	//http.ListenAndServe("localhost:8000", db)
+	//mux := http.NewServeMux()
+	//mux.Handle("/list", http.HandlerFunc(db.list))
+	//mux.Handle("/price", http.HandlerFunc(db.price))
+	//http.ListenAndServe("localhost:8000", mux)
+	http.HandleFunc("/list", db.list)
+	http.HandleFunc("/price", db.price)
+	http.ListenAndServe("localhost:8000", nil)
+}