add -h flag and document flags

fermi.go

@@ -65,7 +65,8 @@ func (fs FilledSamples) Samples() []float64 {
 }
 
 /* Constants */
-const HELP_MSG = "  Operation | Variable assignment | Special\n" +
+const HELP_MSG = "1. Grammar:\n" +
+	"  Operation | Variable assignment | Special\n" +
 	"    Operation:                             operator operand\n" +
 	"          operator:                        (empty) | * | / | + | -\n" +
 	"          operand:                         scalar | lognormal | beta | variable\n" +
@@ -75,6 +76,7 @@ const HELP_MSG = "  Operation | Variable assignment | Special\n" +
 	"    Variable assignment and clear stack:   =. variable_name\n" +
 	"    Special commands: \n" +
 	"         Comment:                          # this is a comment\n" +
+	"         Summary stats:                    stats\n" +
 	"         Clear stack:                      clear | c | .\n" +
 	"         Print debug info:                 debug | d\n" +
 	"         Print help message:               help  | h\n" +
@@ -98,7 +100,16 @@ const HELP_MSG = "  Operation | Variable assignment | Special\n" +
 	"    1 10\n" +
 	"    + beta 1 100\n" +
 	"    )\n" +
-	"    exit\n"
+	"    exit\n" +
+	"\n" +
+	"2. Command flags:\n" +
+	"  -echo\n" +
+	"        Specifies whether inputs should be echoed back. Useful if reading from a file\n." +
+	"  -f string\n" +
+	"        Specifies a file with a model to run\n" +
+	"  -n int\n" +
+	"        Specifies the number of samples to draw when using samples (default 100000)\n" +
+	"  -h    Shows help message\n"
 
 const NORMAL90CONFIDENCE = 1.6448536269514727
 const INIT_DIST Scalar = Scalar(1)
@@ -450,8 +461,12 @@ func main() {
 	num_samples_flag := flag.Int("n", N_SAMPLES, "Specifies the number of samples to draw when using samples")
 	filename := flag.String("f", "", "Specifies a file with a model to run")
 	echo_flag := flag.Bool("echo", false, "Specifies whether inputs should be echoed back. Useful if reading from a file.")
+	help_flag := flag.Bool("h", false, "Shows help message")
 	flag.Parse()
 	N_SAMPLES = *num_samples_flag
+	if *help_flag {
+		fmt.Println(HELP_MSG)
+	}
 
 	var reader *bufio.Reader = nil
 	if *filename != "" {