diff --git a/cmd/repl/main.go b/cmd/repl/main.go
deleted file mode 100644
index 2bce704..0000000
--- a/cmd/repl/main.go
+++ /dev/null
@@ -1,111 +0,0 @@
-package main
-
-import (
-	"bufio"
-	"fmt"
-	"io"
-	"os"
-	"os/user"
-
-	"github.com/d5/tengo/compiler"
-	"github.com/d5/tengo/compiler/ast"
-	"github.com/d5/tengo/compiler/parser"
-	"github.com/d5/tengo/compiler/source"
-	"github.com/d5/tengo/objects"
-	"github.com/d5/tengo/runtime"
-)
-
-const (
-	Prompt = ">> "
-)
-
-func main() {
-	currentUser, err := user.Current()
-	if err != nil {
-		panic(err)
-	}
-
-	fmt.Printf("Hello, %s! Welcome to the Tengo Language!\n", currentUser.Name)
-
-	startRepl(os.Stdin, os.Stdout)
-}
-
-func startRepl(in io.Reader, out io.Writer) {
-	stdin := bufio.NewScanner(in)
-
-	fileSet := source.NewFileSet()
-	globals := make([]*objects.Object, runtime.GlobalsSize)
-	symbolTable := compiler.NewSymbolTable()
-
-	for {
-		_, _ = fmt.Fprintf(out, Prompt)
-
-		scanned := stdin.Scan()
-		if !scanned {
-			return
-		}
-
-		line := stdin.Text()
-
-		file, err := parser.ParseFile(fileSet.AddFile("test", -1, len(line)), []byte(line), nil)
-		if err != nil {
-			_, _ = fmt.Fprintf(out, "error: %s\n", err.Error())
-			continue
-		}
-
-		file = addPrints(file)
-
-		c := compiler.NewCompiler(symbolTable, nil)
-		if err := c.Compile(file); err != nil {
-			_, _ = fmt.Fprintf(out, "Compilation error:\n %s\n", err.Error())
-			continue
-		}
-
-		machine := runtime.NewVM(c.Bytecode(), globals)
-		if err != nil {
-			_, _ = fmt.Fprintf(out, "VM error:\n %s\n", err.Error())
-			continue
-		}
-		if err := machine.Run(); err != nil {
-			_, _ = fmt.Fprintf(out, "Execution error:\n %s\n", err.Error())
-			continue
-		}
-	}
-}
-
-func addPrints(file *ast.File) *ast.File {
-	var stmts []ast.Stmt
-	for _, s := range file.Stmts {
-		switch s := s.(type) {
-		case *ast.ExprStmt:
-			stmts = append(stmts, &ast.ExprStmt{
-				Expr: &ast.CallExpr{
-					Func: &ast.Ident{
-						Name: "print",
-					},
-					Args: []ast.Expr{s.Expr},
-				},
-			})
-
-		case *ast.AssignStmt:
-			stmts = append(stmts, s)
-
-			stmts = append(stmts, &ast.ExprStmt{
-				Expr: &ast.CallExpr{
-					Func: &ast.Ident{
-						Name: "print",
-					},
-					Args: s.Lhs,
-				},
-			})
-
-		default:
-			stmts = append(stmts, s)
-		}
-	}
-
-	return &ast.File{
-		InputFile: file.InputFile,
-		Stmts:     stmts,
-	}
-}
diff --git a/cmd/tengo/main.go b/cmd/tengo/main.go
index 51b425c..1928dd7 100644
--- a/cmd/tengo/main.go
+++ b/cmd/tengo/main.go
@@ -1,9 +1,11 @@
 package main
 
 import (
+	"bufio"
 	"bytes"
 	"flag"
 	"fmt"
+	"io"
 	"io/ioutil"
 	"os"
 	"path/filepath"
@@ -11,31 +13,44 @@ import (
 
 	"github.com/d5/tengo"
 	"github.com/d5/tengo/compiler"
+	"github.com/d5/tengo/compiler/ast"
+	"github.com/d5/tengo/compiler/parser"
+	"github.com/d5/tengo/compiler/source"
+	"github.com/d5/tengo/objects"
 	"github.com/d5/tengo/runtime"
 )
 
 const (
 	sourceFileExt = ".tengo"
+	replPrompt    = ">> "
 )
 
 var (
 	compile    bool
+	showHelp   bool
 	outputFile = flag.String("o", "", "Output file")
 )
 
 func init() {
+	flag.BoolVar(&showHelp, "help", false, "Show help")
 	flag.BoolVar(&compile, "compile", false, "Compile input file")
 	flag.BoolVar(&compile, "c", false, "Compile input file")
 	flag.Parse()
 }
 
 func main() {
-	inputFile := flag.Arg(0)
-	if inputFile == "" {
+	if showHelp {
 		doHelp()
 		os.Exit(2)
 	}
 
+	inputFile := flag.Arg(0)
+	if inputFile == "" {
+		// REPL
+		doRepl(os.Stdin, os.Stdout)
+		return
+	}
+
 	inputData, err := ioutil.ReadFile(inputFile)
 	if err != nil {
 		_, _ = fmt.Fprintf(os.Stderr, "Error reading input file: %s", err.Error())
@@ -65,7 +80,7 @@ func doHelp() {
 	fmt.Println()
 	fmt.Println("Usage:")
 	fmt.Println()
-	fmt.Println("	tengo [flags] input-file")
+	fmt.Println("	tengo [flags] [input-file]")
 	fmt.Println()
 	fmt.Println("Flags:")
 	fmt.Println()
@@ -74,11 +89,17 @@ func doHelp() {
 	fmt.Println()
 	fmt.Println("Examples:")
 	fmt.Println()
-	fmt.Println("	tengo -c -o program.out program.tengo")
-	fmt.Println("	            : Compile program.tengo and write compiled binary to program.out file")
+	fmt.Println("	tengo")
+	fmt.Println("	            : Start Tengo REPL")
 	fmt.Println()
-	fmt.Println("	tengo program.out")
-	fmt.Println("	            : Execute compiled binary program.out")
+	fmt.Println("	tengo myapp.tengo")
+	fmt.Println("	            : Compile and execute a Tengo code (myapp.tengo)")
+	fmt.Println()
+	fmt.Println("	tengo -c -o myapp myapp.tengo")
+	fmt.Println("	            : Compile a Tengo code (myapp.tengo) into compiled binary (myapp)")
+	fmt.Println()
+	fmt.Println("	tengo myapp")
+	fmt.Println("	            : Execute compiled binary (myapp)")
 	fmt.Println()
 	fmt.Println()
 }
@@ -148,6 +169,86 @@ func doRun(data []byte, _, _ string) (err error) {
 	return
 }
 
+func doRepl(in io.Reader, out io.Writer) {
+	stdin := bufio.NewScanner(in)
+
+	fileSet := source.NewFileSet()
+	globals := make([]*objects.Object, runtime.GlobalsSize)
+	symbolTable := compiler.NewSymbolTable()
+
+	for {
+		_, _ = fmt.Fprintf(out, replPrompt)
+
+		scanned := stdin.Scan()
+		if !scanned {
+			return
+		}
+
+		line := stdin.Text()
+
+		file, err := parser.ParseFile(fileSet.AddFile("test", -1, len(line)), []byte(line), nil)
+		if err != nil {
+			_, _ = fmt.Fprintf(out, "error: %s\n", err.Error())
+			continue
+		}
+
+		file = addPrints(file)
+
+		c := compiler.NewCompiler(symbolTable, nil)
+		if err := c.Compile(file); err != nil {
+			_, _ = fmt.Fprintf(out, "Compilation error:\n %s\n", err.Error())
+			continue
+		}
+
+		machine := runtime.NewVM(c.Bytecode(), globals)
+		if err != nil {
+			_, _ = fmt.Fprintf(out, "VM error:\n %s\n", err.Error())
+			continue
+		}
+		if err := machine.Run(); err != nil {
+			_, _ = fmt.Fprintf(out, "Execution error:\n %s\n", err.Error())
+			continue
+		}
+	}
+}
+
+func addPrints(file *ast.File) *ast.File {
+	var stmts []ast.Stmt
+	for _, s := range file.Stmts {
+		switch s := s.(type) {
+		case *ast.ExprStmt:
+			stmts = append(stmts, &ast.ExprStmt{
+				Expr: &ast.CallExpr{
+					Func: &ast.Ident{
+						Name: "print",
+					},
+					Args: []ast.Expr{s.Expr},
+				},
+			})
+
+		case *ast.AssignStmt:
+			stmts = append(stmts, s)
+
+			stmts = append(stmts, &ast.ExprStmt{
+				Expr: &ast.CallExpr{
+					Func: &ast.Ident{
+						Name: "print",
+					},
+					Args: s.Lhs,
+				},
+			})
+
+		default:
+			stmts = append(stmts, s)
+		}
+	}
+
+	return &ast.File{
+		InputFile: file.InputFile,
+		Stmts:     stmts,
+	}
+}
+
 func basename(s string) string {
 	s = filepath.Base(s)