add --list (or -l) flag to print existing tasks

If an inexixtent task is given, the help also prints as before

Also fixing README documentation

Closes #51

README.md

@@ -379,7 +379,8 @@ print-os:
 
 ### Help
 
-Running `task help` lists all tasks with a description. The following taskfile:
+Running `task --list` (or `task -l`) lists all tasks with a description.
+The following taskfile:
 
 ```yml
 build:
@@ -404,8 +405,8 @@ css:
 would print the following output:
 
 ```bash
-build   Build the go binary.
-test    Run all the go tests.
+* build:   Build the go binary.
+* test:    Run all the go tests.
 ```
 
 ## Watch tasks (experimental)

cmd/task/task.go

@@ -14,7 +14,7 @@ var (
 	version = "master"
 )
 
-const usage = `Usage: task [-ifwv] [--init] [--force] [--watch] [--verbose] [task...]
+const usage = `Usage: task [-ilfwv] [--init] [--list] [--force] [--watch] [--verbose] [task...]
 
 Runs the specified task(s). Falls back to the "default" task if no task name
 was specified, or lists all tasks if an unknown task name was specified.
@@ -45,6 +45,7 @@ func main() {
 	var (
 		versionFlag bool
 		init        bool
+		list        bool
 		force       bool
 		watch       bool
 		verbose     bool
@@ -52,6 +53,7 @@ func main() {
 
 	pflag.BoolVar(&versionFlag, "version", false, "show Task version")
 	pflag.BoolVarP(&init, "init", "i", false, "creates a new Taskfile.yml in the current folder")
+	pflag.BoolVarP(&list, "list", "l", false, "lists tasks with description of current Taskfile")
 	pflag.BoolVarP(&force, "force", "f", false, "forces execution even when the task is up-to-date")
 	pflag.BoolVarP(&watch, "watch", "w", false, "enables watch of the given task")
 	pflag.BoolVarP(&verbose, "verbose", "v", false, "enables verbose mode")
@@ -86,6 +88,11 @@ func main() {
 		log.Fatal(err)
 	}
 
+	if list {
+		e.PrintTasksHelp()
+		return
+	}
+
 	args := pflag.Args()
 	if len(args) == 0 {
 		log.Println("task: No argument given, trying default task")

help.go

@@ -6,7 +6,8 @@ import (
 	"text/tabwriter"
 )
 
-func (e *Executor) printExistingTasksHelp() {
+// PrintTasksHelp prints help os tasks that have a description
+func (e *Executor) PrintTasksHelp() {
 	tasks := e.tasksWithDesc()
 	if len(tasks) == 0 {
 		return
@@ -16,7 +17,7 @@ func (e *Executor) printExistingTasksHelp() {
 	// Format in tab-separated columns with a tab stop of 8.
 	w := tabwriter.NewWriter(e.Stdout, 0, 8, 0, '\t', 0)
 	for _, task := range tasks {
-		fmt.Fprintln(w, fmt.Sprintf("- %s:\t%s", task, e.Tasks[task].Desc))
+		fmt.Fprintln(w, fmt.Sprintf("* %s:\t%s", task, e.Tasks[task].Desc))
 	}
 	w.Flush()
 }

task.go

@@ -85,7 +85,7 @@ func (e *Executor) Run(args ...string) error {
 	for _, a := range args {
 		if _, ok := e.Tasks[a]; !ok {
 			// FIXME: move to the main package
-			e.printExistingTasksHelp()
+			e.PrintTasksHelp()
 			return &taskNotFoundError{taskName: a}
 		}
 	}