Wire up file running.

golox/cmd/golox/main.go

@@ -1,6 +1,7 @@
 package main
 
 import (
+	"errors"
 	"fmt"
 	"os"
 
@@ -9,12 +10,17 @@ import (
 
 func main() {
 	argc := len(os.Args)
-	if argc > 2 {
+	switch {
+	case argc > 2:
 		fmt.Println("Usage: golox [script]")
 		os.Exit(64)
-	} else if argc == 2 {
-
-	} else {
+	case argc == 2:
+		err := runner.RunFile(os.Args[1])
+		if errors.Is(err, runner.ErrInvalidScriptFile) {
+			fmt.Println(err)
+			os.Exit(1)
+		}
+	default:
 		runner.RunPrompt()
 	}
 }

golox/internal/runner/runner.go

@@ -2,10 +2,13 @@ package runner
 
 import (
 	"bufio"
+	"errors"
 	"fmt"
 	"os"
 )
 
+var ErrInvalidScriptFile = errors.New("could not read script file")
+
 func RunPrompt() {
 	s := bufio.NewScanner(os.Stdin)
 	fmt.Print("> ")
@@ -20,7 +23,7 @@ func RunPrompt() {
 func RunFile(path string) error {
 	fBytes, err := os.ReadFile(path)
 	if err != nil {
-		return fmt.Errorf("could not read script file: %w", err)
+		return errors.Join(ErrInvalidScriptFile, err)
 	}
 	Run(string(fBytes))
 	// TODO: check hadError and exit with a 65 code if so.

golox/test.lox

@@ -0,0 +1 @@
+{,{.(;)-}}*