Update README.md and HACKING.md and resulting yak shave.

sky/tools/skygo/sky_server.go

Index: sky/tools/skygo/sky_server.go
diff --git a/sky/tools/skygo/sky_server.go b/sky/tools/skygo/sky_server.go
index 1327a19d3c6c8628ba2a5b7c18ec12d9aca33fc4..3b6ac706c651d8a2709bc37df12cb8462cd020d9 100644
--- a/sky/tools/skygo/sky_server.go
+++ b/sky/tools/skygo/sky_server.go
@@ -15,6 +15,8 @@ import (
 	"strings"
 )
 
+var verbose bool = false;
+
 type skyHandlerRoot struct {
 	root string
 }
@@ -29,63 +31,70 @@ func (handler *skyHandlerRoot) ServeHTTP(w http.ResponseWriter, r *http.Request)
 		return
 	}
 	path := path.Join(handler.root, r.URL.Path)
+
+        // Remove this one once .sky files are gone:
 	if strings.HasSuffix(path, ".sky") {
 		w.Header().Set("Content-Type", "text/sky")
 	}
+
+	if strings.HasSuffix(path, ".dart") {
+		w.Header().Set("Content-Type", "application/dart")
+	}
 	w.Header().Set("Cache-Control", "no-cache")
 	http.ServeFile(w, r, path)
 }
 
 func usage() {
-	fmt.Fprintf(os.Stderr, "Usage: sky_server [flags] MOJO_SRC_ROOT PORT\n\n")
-	fmt.Fprintf(os.Stderr, "launches a basic http server with mappings into the\n")
-	fmt.Fprintf(os.Stderr, "mojo repository for framework/service paths.\n")
-	fmt.Fprintf(os.Stderr, "[flags] MUST be before arguments, because go:flag.\n\n")
+	fmt.Fprintf(os.Stderr, "Usage: sky_server [flags] MOJO_SRC_ROOT PACKAGE_ROOT\n")
+	fmt.Fprintf(os.Stderr, "Launches a basic http server with mappings into the mojo repository for framework/service paths.\n")
+	fmt.Fprintf(os.Stderr, "MOJO_SRC_ROOT must be the root of the Mojo repository.\n")
+	fmt.Fprintf(os.Stderr, "PACKAGE_ROOT must be the root of your Dart packages (e.g. out/Debug/gen/dart-pkg/packages/).\n")
 	flag.PrintDefaults()
 	os.Exit(2)
 }
 
 func addMapping(from_path string, to_path string) {
-	// Print to stderr to it's more obvious what this binary does.
-	fmt.Fprintf(os.Stderr, "  %s -> %s\n", from_path, to_path)
+	if (verbose) {
+		fmt.Fprintf(os.Stderr, "  %s -> %s\n", from_path, to_path)
+	}
 	http.Handle(from_path, http.StripPrefix(from_path, skyHandler(to_path)))
 }
 
-func main() {
-	var configuration = flag.String("t", "Release", "The target configuration (i.e. Release or Debug)")
-
-	flag.Parse()
-	flag.Usage = usage
-	// The built-in go:flag is awful.  It only allows short-name arguments
-	// and they *must* be before any unnamed arguments.  There are better ones:
-	// https://godoc.org/github.com/jessevdk/go-flags
-	// but for now we're using raw-go.
-	if flag.NArg() != 3 {
-		usage()
+func setupMappings(mojoRoot string, packageRoot string, port int) {
+	if (verbose) {
+		fmt.Fprintf(os.Stderr, "Mappings for localhost:%v:\n", port)
+		fmt.Fprintf(os.Stderr, "  / -> %s\n", mojoRoot)
 	}
+	http.Handle("/", skyHandler(mojoRoot))
 
-	root, _ := filepath.Abs(flag.Arg(0))
-	port := flag.Arg(1)
-	packageRoot := flag.Arg(2)
-
-	// genRoot should not be needed once we figure out how mojom generation
-	// for sdk users should work.
-	genRoot := path.Join(root, "out", *configuration, "gen")
-
-	fmt.Fprintf(os.Stderr, "Mappings for localhost:%s:\n", port)
-
-	fmt.Fprintf(os.Stderr, "  / -> %s\n", root)
-	http.Handle("/", skyHandler(root))
-
-	fmt.Fprintf(os.Stderr, "  /echo_post -> custom echo handler\n")
+	if (verbose) {
+		fmt.Fprintf(os.Stderr, "  /echo_post -> custom echo handler\n")
+	}
 	http.HandleFunc("/echo_post", func(w http.ResponseWriter, r *http.Request) {
 		defer r.Body.Close()
 		body, _ := ioutil.ReadAll(r.Body)
 		w.Write(body)
 	})
 
-	addMapping("/gen/", genRoot)
 	addMapping("/packages/", packageRoot)
+}
+
+func main() {
+	var portPtr = flag.Int("p", 8000, "The HTTP port")
+	var verbosePtr = flag.Bool("v", false, "Verbose mode. Without this flag, the default behaviour only reports errors.")
+	flag.Parse()
+	flag.Usage = usage
+	if flag.NArg() != 2 {
+		usage()
+	}
+
+	var port int = *portPtr;
+	verbose = *verbosePtr;
+
+	root, _ := filepath.Abs(flag.Arg(0))
+	packageRoot := flag.Arg(1)
+
+	setupMappings(root, packageRoot, port);
 
-	http.ListenAndServe(":"+port, nil)
+	http.ListenAndServe(fmt.Sprintf(":%v", port), nil)
 }