feat: statistics flag, commented some more

internal/config/parse_from_args.go

@@ -7,13 +7,14 @@ import (
 
 // Extract the program configuration from the command-line arguments.
 func FromArgs() (*Config, error) {
-	// Parse flags.
+	// Relevant flags.
 	verbose := flag.Bool("v", false, "Verbosity. If set, the program will print logs.")
 	explanation := flag.Bool("x", false, "Explanation. Whether or not to show all reduction steps.")
+	statistics := flag.Bool("s", false, "Statistics. If set, the process will print various statistics about the run.")
 	profile := flag.String("p", "", "CPU profiling. If set, the program will run a performance profile during execution.")
 	flag.Parse()
 
-	// Parse non-flag arguments.
+	// There must only be one input argument.
 	if flag.NArg() == 0 {
 		return nil, fmt.Errorf("no input given")
 	} else if flag.NArg() > 1 {
@@ -25,7 +26,7 @@ func FromArgs() (*Config, error) {
 	if flag.Arg(0) == "-" {
 		source = StdinSource{}
 	} else {
-		source = StringSource{data: flag.Arg(0)}
+		source = StringSource{Data: flag.Arg(0)}
 	}
 
 	return &Config{
@@ -33,5 +34,6 @@ func FromArgs() (*Config, error) {
 		Verbose:     *verbose,
 		Explanation: *explanation,
 		Profile:     *profile,
+		Statistics:  *statistics,
 	}, nil
 }