Merge pull request #62 from d5/v1prep

v1 release prep

.gitignore

@@ -1 +1 @@
-bin/
+dist/

.goreleaser.yml

@@ -0,0 +1,15 @@
+builds:
+  - env:
+      - CGO_ENABLED=0
+    main: ./cmd/tengo/main.go
+    goos:
+      - darwin
+      - linux
+      - windows
+archive:
+  files:
+    - none*
+checksum:
+  name_template: 'checksums.txt'
+changelog:
+  sort: asc

.travis.yml

@@ -8,3 +8,10 @@ install:
 
 script:
   - make test
+
+deploy:
+  - provider: script
+    skip_cleanup: true
+    script: curl -sL https://git.io/goreleaser | bash
+    on:
+      tags: true

README.md

@@ -47,16 +47,16 @@ s := sum("", [1, 2, 3])  // == "123"
 | | fib(35) | fibt(35) |  Type  |
 | :--- |    ---: |     ---: |  :---: |
 | Go | `58ms` | `4ms` | Go (native) |
-| [**Tengo**](https://github.com/d5/tengo) | `4,334ms` | `5ms` | VM on Go |
+| [**Tengo**](https://github.com/d5/tengo) | `4,180ms` | `5ms` | VM on Go |
-| Lua | `1,740ms` | `3ms` | Lua (native) |
+| Lua | `1,695ms` | `3ms` | Lua (native) |
-| [go-lua](https://github.com/Shopify/go-lua) | `5,229ms` | `5ms` | Lua VM on Go |
+| [go-lua](https://github.com/Shopify/go-lua) | `5,163ms` | `5ms` | Lua VM on Go |
-| [GopherLua](https://github.com/yuin/gopher-lua) | `5,486ms` | `5ms` | Lua VM on Go |
+| [GopherLua](https://github.com/yuin/gopher-lua) | `5,525ms` | `5ms` | Lua VM on Go |
-| Python | `3,116ms` | `27ms` | Python (native) |
+| Python | `3,097ms` | `27ms` | Python (native) |
-| [starlark-go](https://github.com/google/starlark-go) | `15,414ms` | `5ms` | Python-like Interpreter on Go |
+| [starlark-go](https://github.com/google/starlark-go) | `15,307ms` | `5ms` | Python-like Interpreter on Go |
-| [gpython](https://github.com/go-python/gpython) | `17,754ms` | `6ms` | Python Interpreter on Go |
+| [gpython](https://github.com/go-python/gpython) | `17,656ms` | `5ms` | Python Interpreter on Go |
-| [goja](https://github.com/dop251/goja) | `6,843ms` | `6ms` | JS VM on Go |
+| [goja](https://github.com/dop251/goja) | `6,876ms` | `5ms` | JS VM on Go |
-| [otto](https://github.com/robertkrimen/otto) | `86,542ms` | `13ms` | JS Interpreter on Go |
+| [otto](https://github.com/robertkrimen/otto) | `81,886ms` | `12ms` | JS Interpreter on Go |
-| [Anko](https://github.com/mattn/anko) | `98,962ms` | `26ms` | Interpreter on Go |
+| [Anko](https://github.com/mattn/anko) | `97,517ms` | `14ms` | Interpreter on Go |
 
 _* [fib(35)](https://github.com/d5/tengobench/blob/master/code/fib.tengo): Fibonacci(35)_  
 _* [fibt(35)](https://github.com/d5/tengobench/blob/master/code/fibtc.tengo): [tail-call](https://en.wikipedia.org/wiki/Tail_call) version of Fibonacci(35)_  
@@ -72,24 +72,3 @@ _* See [here](https://github.com/d5/tengobench) for commands/codes used_
 - [Interoperability](https://github.com/d5/tengo/blob/master/docs/interoperability.md)
 - [Tengo CLI](https://github.com/d5/tengo/blob/master/docs/tengo-cli.md)
 - [Standard Library](https://github.com/d5/tengo/blob/master/docs/stdlib.md)
-
-## Roadmap
-
-### v0. _(Current)_
-
-Things are experimental, and, the focus is on the **core language features**, **stability**, **basic interoperability**, and the **performance optimization**.
-
-### [v1. Tengo as a Script Language](https://github.com/d5/tengo/labels/v1.0)
-
-This will be the first _versioned_ release, and, the main goal for v1 is to make Tengo as a _fast_ embeddable script language for Go, which means Tengo will be comparable to other Go-based script languages such as [Starlark](https://github.com/google/starlark-go), [Lua](https://github.com/Shopify/go-lua) [VM](https://github.com/yuin/gopher-lua)s, and [other](https://github.com/robertkrimen/otto) [interpreter](https://github.com/mattn/anko)s.
-
-- Interoperability with Go code
-- Sandbox environment
-- More language features
-
-### v2. Tengo as a Standalone Language
-
-- Language-level concurrency support
-- Tengo Standard Libraries
-- Native executables compilation
-- More language features

cmd/tengo/main.go

@@ -25,15 +25,16 @@ const (
 )
 
 var (
-	compile    bool
+	compileOutput string
-	showHelp   bool
+	showHelp      bool
-	outputFile = flag.String("o", "", "Output file")
+	showVersion   bool
+	version       = "dev"
 )
 
 func init() {
 	flag.BoolVar(&showHelp, "help", false, "Show help")
-	flag.BoolVar(&compile, "compile", false, "Compile input file")
+	flag.StringVar(&compileOutput, "o", "", "Compile output file")
-	flag.BoolVar(&compile, "c", false, "Compile input file")
+	flag.BoolVar(&showVersion, "version", false, "Show version")
 	flag.Parse()
 }
 
@@ -41,12 +42,15 @@ func main() {
 	if showHelp {
 		doHelp()
 		os.Exit(2)
+	} else if showVersion {
+		fmt.Println(version)
+		return
 	}
 
 	inputFile := flag.Arg(0)
 	if inputFile == "" {
 		// REPL
-		doRepl(os.Stdin, os.Stdout)
+		runREPL(os.Stdin, os.Stdout)
 		return
 	}
 
@@ -56,18 +60,18 @@ func main() {
 		os.Exit(1)
 	}
 
-	if compile {
+	if compileOutput != "" {
-		if err := doCompile(inputData, inputFile, *outputFile); err != nil {
+		if err := compileOnly(inputData, inputFile, compileOutput); err != nil {
 			_, _ = fmt.Fprintln(os.Stderr, err.Error())
 			os.Exit(1)
 		}
 	} else if filepath.Ext(inputFile) == sourceFileExt {
-		if err := doCompileRun(inputData, inputFile, *outputFile); err != nil {
+		if err := compileAndRun(inputData, inputFile); err != nil {
 			_, _ = fmt.Fprintln(os.Stderr, err.Error())
 			os.Exit(1)
 		}
 	} else {
-		if err := doRun(inputData, inputFile, *outputFile); err != nil {
+		if err := runCompiled(inputData); err != nil {
 			_, _ = fmt.Fprintln(os.Stderr, err.Error())
 			os.Exit(1)
 		}
@@ -81,27 +85,32 @@ func doHelp() {
 	fmt.Println()
 	fmt.Println("Flags:")
 	fmt.Println()
-	fmt.Println("	-c/-compile compile the input and produce bytecode file")
+	fmt.Println("	-o        compile output file")
-	fmt.Println("	-o          output")
+	fmt.Println("	-version  show version")
 	fmt.Println()
 	fmt.Println("Examples:")
 	fmt.Println()
 	fmt.Println("	tengo")
-	fmt.Println("	            : Start Tengo REPL")
+	fmt.Println()
+	fmt.Println("	          Start Tengo REPL")
 	fmt.Println()
 	fmt.Println("	tengo myapp.tengo")
-	fmt.Println("	            : Compile and execute source file (myapp.tengo)")
 	fmt.Println()
-	fmt.Println("	tengo -c myapp myapp.tengo")
+	fmt.Println("	          Compile and run source file (myapp.tengo)")
-	fmt.Println("	            : Compile source file (myapp.tengo) and produce bytecode file (myapp)")
+	fmt.Println("	          Source file must have .tengo extension")
+	fmt.Println()
+	fmt.Println("	tengo -o myapp myapp.tengo")
+	fmt.Println()
+	fmt.Println("	          Compile source file (myapp.tengo) into bytecode file (myapp)")
 	fmt.Println()
 	fmt.Println("	tengo myapp")
-	fmt.Println("	            : Execute bytecode file (myapp)")
+	fmt.Println()
+	fmt.Println("	          Run bytecode file (myapp)")
 	fmt.Println()
 	fmt.Println()
 }
 
-func doCompile(data []byte, inputFile, outputFile string) (err error) {
+func compileOnly(data []byte, inputFile, outputFile string) (err error) {
 	bytecode, err := compileSrc(data, filepath.Base(inputFile))
 	if err != nil {
 		return
@@ -133,7 +142,7 @@ func doCompile(data []byte, inputFile, outputFile string) (err error) {
 	return
 }
 
-func doCompileRun(data []byte, inputFile, _ string) (err error) {
+func compileAndRun(data []byte, inputFile string) (err error) {
 	bytecode, err := compileSrc(data, filepath.Base(inputFile))
 	if err != nil {
 		return
@@ -149,7 +158,7 @@ func doCompileRun(data []byte, inputFile, _ string) (err error) {
 	return
 }
 
-func doRun(data []byte, _, _ string) (err error) {
+func runCompiled(data []byte) (err error) {
 	bytecode := &compiler.Bytecode{}
 	err = bytecode.Decode(bytes.NewReader(data))
 	if err != nil {
@@ -166,7 +175,7 @@ func doRun(data []byte, _, _ string) (err error) {
 	return
 }
 
-func doRepl(in io.Reader, out io.Writer) {
+func runREPL(in io.Reader, out io.Writer) {
 	stdin := bufio.NewScanner(in)
 
 	fileSet := source.NewFileSet()

compiler/ast/return_stmt.go

@@ -1,15 +1,13 @@
 package ast
 
 import (
-	"strings"
-
 	"github.com/d5/tengo/compiler/source"
 )
 
 // ReturnStmt represents a return statement.
 type ReturnStmt struct {
 	ReturnPos source.Pos
-	Results   []Expr
+	Result    Expr
 }
 
 func (s *ReturnStmt) stmtNode() {}
@@ -21,21 +19,16 @@ func (s *ReturnStmt) Pos() source.Pos {
 
 // End returns the position of first character immediately after the node.
 func (s *ReturnStmt) End() source.Pos {
-	if n := len(s.Results); n > 0 {
+	if s.Result != nil {
-		return s.Results[n-1].End()
+		return s.Result.End()
 	}
 
 	return s.ReturnPos + 6
 }
 
 func (s *ReturnStmt) String() string {
-	if len(s.Results) > 0 {
+	if s.Result != nil {
-		var res []string
+		return "return " + s.Result.String()
-		for _, e := range s.Results {
-			res = append(res, e.String())
-		}
-
-		return "return " + strings.Join(res, ", ")
 	}
 
 	return "return"

compiler/bytecode.go

@@ -85,4 +85,5 @@ func init() {
 	gob.Register(&objects.MapIterator{})
 	gob.Register(&objects.ArrayIterator{})
 	gob.Register(&objects.Time{})
+	gob.Register(&objects.CompiledModule{})
 }

compiler/bytecode_test.go

@@ -69,20 +69,20 @@ func TestBytecode(t *testing.T) {
 				compiler.MakeInstruction(compiler.OpAdd),
 				compiler.MakeInstruction(compiler.OpGetLocal, 0),
 				compiler.MakeInstruction(compiler.OpAdd),
-				compiler.MakeInstruction(compiler.OpReturnValue, 1)),
+				compiler.MakeInstruction(compiler.OpReturnValue)),
 			compiledFunction(1, 0,
 				compiler.MakeInstruction(compiler.OpConstant, 2),
 				compiler.MakeInstruction(compiler.OpSetLocal, 0),
 				compiler.MakeInstruction(compiler.OpGetFree, 0),
 				compiler.MakeInstruction(compiler.OpGetLocal, 0),
 				compiler.MakeInstruction(compiler.OpClosure, 4, 2),
-				compiler.MakeInstruction(compiler.OpReturnValue, 1)),
+				compiler.MakeInstruction(compiler.OpReturnValue)),
 			compiledFunction(1, 0,
 				compiler.MakeInstruction(compiler.OpConstant, 1),
 				compiler.MakeInstruction(compiler.OpSetLocal, 0),
 				compiler.MakeInstruction(compiler.OpGetLocal, 0),
 				compiler.MakeInstruction(compiler.OpClosure, 5, 1),
-				compiler.MakeInstruction(compiler.OpReturnValue, 1)))))
+				compiler.MakeInstruction(compiler.OpReturnValue)))))
 }
 
 func testBytecodeSerialization(t *testing.T, b *compiler.Bytecode) {

compiler/compiler.go

@@ -426,17 +426,14 @@ func (c *Compiler) Compile(node ast.Node) error {
 			return fmt.Errorf("return statement outside function")
 		}
 
-		switch len(node.Results) {
+		if node.Result == nil {
-		case 0:
 			c.emit(OpReturn)
-		case 1:
+		} else {
-			if err := c.Compile(node.Results[0]); err != nil {
+			if err := c.Compile(node.Result); err != nil {
 				return err
 			}
 
-			c.emit(OpReturnValue, 1)
+			c.emit(OpReturnValue)
-		default:
-			return fmt.Errorf("multi-value return not implemented")
 		}
 
 	case *ast.CallExpr:

compiler/compiler_test.go

@@ -446,7 +446,7 @@ func TestCompiler_Compile(t *testing.T) {
 					compiler.MakeInstruction(compiler.OpConstant, 0),
 					compiler.MakeInstruction(compiler.OpConstant, 1),
 					compiler.MakeInstruction(compiler.OpAdd),
-					compiler.MakeInstruction(compiler.OpReturnValue, 1)))))
+					compiler.MakeInstruction(compiler.OpReturnValue)))))
 
 	expect(t, `func() { 5 + 10 }`,
 		bytecode(
@@ -490,7 +490,7 @@ func TestCompiler_Compile(t *testing.T) {
 					compiler.MakeInstruction(compiler.OpConstant, 0),
 					compiler.MakeInstruction(compiler.OpPop),
 					compiler.MakeInstruction(compiler.OpConstant, 1),
-					compiler.MakeInstruction(compiler.OpReturnValue, 1)))))
+					compiler.MakeInstruction(compiler.OpReturnValue)))))
 
 	expect(t, `func() { if(true) { return 1 } else { return 2 } }`,
 		bytecode(
@@ -501,13 +501,13 @@ func TestCompiler_Compile(t *testing.T) {
 				intObject(1),
 				intObject(2),
 				compiledFunction(0, 0,
-					compiler.MakeInstruction(compiler.OpTrue),              // 0000
+					compiler.MakeInstruction(compiler.OpTrue),           // 0000
-					compiler.MakeInstruction(compiler.OpJumpFalsy, 12),     // 0001
+					compiler.MakeInstruction(compiler.OpJumpFalsy, 11),  // 0001
-					compiler.MakeInstruction(compiler.OpConstant, 0),       // 0004
+					compiler.MakeInstruction(compiler.OpConstant, 0),    // 0004
-					compiler.MakeInstruction(compiler.OpReturnValue, 1),    // 0007
+					compiler.MakeInstruction(compiler.OpReturnValue),    // 0007
-					compiler.MakeInstruction(compiler.OpJump, 17),          // 0009
+					compiler.MakeInstruction(compiler.OpJump, 15),       // 0008
-					compiler.MakeInstruction(compiler.OpConstant, 1),       // 0012
+					compiler.MakeInstruction(compiler.OpConstant, 1),    // 0011
-					compiler.MakeInstruction(compiler.OpReturnValue, 1))))) // 0014
+					compiler.MakeInstruction(compiler.OpReturnValue))))) // 0014
 
 	expect(t, `func() { 1; if(true) { 2 } else { 3 }; 4 }`,
 		bytecode(
@@ -564,7 +564,7 @@ func TestCompiler_Compile(t *testing.T) {
 				intObject(24),
 				compiledFunction(0, 0,
 					compiler.MakeInstruction(compiler.OpConstant, 0),
-					compiler.MakeInstruction(compiler.OpReturnValue, 1)))))
+					compiler.MakeInstruction(compiler.OpReturnValue)))))
 
 	expect(t, `noArg := func() { 24 }; noArg();`,
 		bytecode(
@@ -593,7 +593,7 @@ func TestCompiler_Compile(t *testing.T) {
 				intObject(24),
 				compiledFunction(0, 0,
 					compiler.MakeInstruction(compiler.OpConstant, 0),
-					compiler.MakeInstruction(compiler.OpReturnValue, 1)))))
+					compiler.MakeInstruction(compiler.OpReturnValue)))))
 
 	expect(t, `n := 55; func() { n };`,
 		bytecode(
@@ -620,23 +620,7 @@ func TestCompiler_Compile(t *testing.T) {
 					compiler.MakeInstruction(compiler.OpConstant, 0),
 					compiler.MakeInstruction(compiler.OpDefineLocal, 0),
 					compiler.MakeInstruction(compiler.OpGetLocal, 0),
-					compiler.MakeInstruction(compiler.OpReturnValue, 1)))))
+					compiler.MakeInstruction(compiler.OpReturnValue)))))
-
-	expect(t, `func() { n := 55; n = 23; return n }`,
-		bytecode(
-			concat(
-				compiler.MakeInstruction(compiler.OpConstant, 2),
-				compiler.MakeInstruction(compiler.OpPop)),
-			objectsArray(
-				intObject(55),
-				intObject(23),
-				compiledFunction(1, 0,
-					compiler.MakeInstruction(compiler.OpConstant, 0),
-					compiler.MakeInstruction(compiler.OpDefineLocal, 0),
-					compiler.MakeInstruction(compiler.OpConstant, 1),
-					compiler.MakeInstruction(compiler.OpSetLocal, 0),
-					compiler.MakeInstruction(compiler.OpGetLocal, 0),
-					compiler.MakeInstruction(compiler.OpReturnValue, 1)))))
 
 	expect(t, `func() { a := 55; b := 77; return a + b }`,
 		bytecode(
@@ -654,7 +638,7 @@ func TestCompiler_Compile(t *testing.T) {
 					compiler.MakeInstruction(compiler.OpGetLocal, 0),
 					compiler.MakeInstruction(compiler.OpGetLocal, 1),
 					compiler.MakeInstruction(compiler.OpAdd),
-					compiler.MakeInstruction(compiler.OpReturnValue, 1)))))
+					compiler.MakeInstruction(compiler.OpReturnValue)))))
 
 	expect(t, `f1 := func(a) { return a }; f1(24);`,
 		bytecode(
@@ -668,7 +652,7 @@ func TestCompiler_Compile(t *testing.T) {
 			objectsArray(
 				compiledFunction(1, 1,
 					compiler.MakeInstruction(compiler.OpGetLocal, 0),
-					compiler.MakeInstruction(compiler.OpReturnValue, 1)),
+					compiler.MakeInstruction(compiler.OpReturnValue)),
 				intObject(24))))
 
 	expect(t, `f1 := func(a, b, c) { a; b; return c; }; f1(24, 25, 26);`,
@@ -689,11 +673,26 @@ func TestCompiler_Compile(t *testing.T) {
 					compiler.MakeInstruction(compiler.OpGetLocal, 1),
 					compiler.MakeInstruction(compiler.OpPop),
 					compiler.MakeInstruction(compiler.OpGetLocal, 2),
-					compiler.MakeInstruction(compiler.OpReturnValue, 1)),
+					compiler.MakeInstruction(compiler.OpReturnValue)),
 				intObject(24),
 				intObject(25),
 				intObject(26))))
 
+	expect(t, `func() { n := 55; n = 23; return n }`,
+		bytecode(
+			concat(
+				compiler.MakeInstruction(compiler.OpConstant, 2),
+				compiler.MakeInstruction(compiler.OpPop)),
+			objectsArray(
+				intObject(55),
+				intObject(23),
+				compiledFunction(1, 0,
+					compiler.MakeInstruction(compiler.OpConstant, 0),
+					compiler.MakeInstruction(compiler.OpDefineLocal, 0),
+					compiler.MakeInstruction(compiler.OpConstant, 1),
+					compiler.MakeInstruction(compiler.OpSetLocal, 0),
+					compiler.MakeInstruction(compiler.OpGetLocal, 0),
+					compiler.MakeInstruction(compiler.OpReturnValue)))))
 	expect(t, `len([]);`,
 		bytecode(
 			concat(
@@ -713,7 +712,7 @@ func TestCompiler_Compile(t *testing.T) {
 					compiler.MakeInstruction(compiler.OpGetBuiltin, 3),
 					compiler.MakeInstruction(compiler.OpArray, 0),
 					compiler.MakeInstruction(compiler.OpCall, 1),
-					compiler.MakeInstruction(compiler.OpReturnValue, 1)))))
+					compiler.MakeInstruction(compiler.OpReturnValue)))))
 
 	expect(t, `func(a) { func(b) { return a + b } }`,
 		bytecode(
@@ -725,7 +724,7 @@ func TestCompiler_Compile(t *testing.T) {
 					compiler.MakeInstruction(compiler.OpGetFree, 0),
 					compiler.MakeInstruction(compiler.OpGetLocal, 0),
 					compiler.MakeInstruction(compiler.OpAdd),
-					compiler.MakeInstruction(compiler.OpReturnValue, 1)),
+					compiler.MakeInstruction(compiler.OpReturnValue)),
 				compiledFunction(1, 1,
 					compiler.MakeInstruction(compiler.OpGetLocal, 0),
 					compiler.MakeInstruction(compiler.OpClosure, 0, 1),
@@ -751,16 +750,16 @@ func(a) {
 					compiler.MakeInstruction(compiler.OpAdd),
 					compiler.MakeInstruction(compiler.OpGetLocal, 0),
 					compiler.MakeInstruction(compiler.OpAdd),
-					compiler.MakeInstruction(compiler.OpReturnValue, 1)),
+					compiler.MakeInstruction(compiler.OpReturnValue)),
 				compiledFunction(1, 1,
 					compiler.MakeInstruction(compiler.OpGetFree, 0),
 					compiler.MakeInstruction(compiler.OpGetLocal, 0),
 					compiler.MakeInstruction(compiler.OpClosure, 0, 2),
-					compiler.MakeInstruction(compiler.OpReturnValue, 1)),
+					compiler.MakeInstruction(compiler.OpReturnValue)),
 				compiledFunction(1, 1,
 					compiler.MakeInstruction(compiler.OpGetLocal, 0),
 					compiler.MakeInstruction(compiler.OpClosure, 1, 1),
-					compiler.MakeInstruction(compiler.OpReturnValue, 1)))))
+					compiler.MakeInstruction(compiler.OpReturnValue)))))
 
 	expect(t, `
 g := 55;
@@ -799,20 +798,20 @@ func() {
 					compiler.MakeInstruction(compiler.OpAdd),
 					compiler.MakeInstruction(compiler.OpGetLocal, 0),
 					compiler.MakeInstruction(compiler.OpAdd),
-					compiler.MakeInstruction(compiler.OpReturnValue, 1)),
+					compiler.MakeInstruction(compiler.OpReturnValue)),
 				compiledFunction(1, 0,
 					compiler.MakeInstruction(compiler.OpConstant, 2),
 					compiler.MakeInstruction(compiler.OpDefineLocal, 0),
 					compiler.MakeInstruction(compiler.OpGetFree, 0),
 					compiler.MakeInstruction(compiler.OpGetLocal, 0),
 					compiler.MakeInstruction(compiler.OpClosure, 4, 2),
-					compiler.MakeInstruction(compiler.OpReturnValue, 1)),
+					compiler.MakeInstruction(compiler.OpReturnValue)),
 				compiledFunction(1, 0,
 					compiler.MakeInstruction(compiler.OpConstant, 1),
 					compiler.MakeInstruction(compiler.OpDefineLocal, 0),
 					compiler.MakeInstruction(compiler.OpGetLocal, 0),
 					compiler.MakeInstruction(compiler.OpClosure, 5, 1),
-					compiler.MakeInstruction(compiler.OpReturnValue, 1)))))
+					compiler.MakeInstruction(compiler.OpReturnValue)))))
 
 	expect(t, `for i:=0; i<10; i++ {}`,
 		bytecode(

compiler/opcodes.go

@@ -157,7 +157,7 @@ var OpcodeOperands = [...][]int{
 	OpSliceIndex:       {},
 	OpCall:             {1},
 	OpReturn:           {},
-	OpReturnValue:      {1},
+	OpReturnValue:      {},
 	OpGetLocal:         {1},
 	OpSetLocal:         {1},
 	OpDefineLocal:      {1},

compiler/parser/parser.go

@@ -862,15 +862,15 @@ func (p *Parser) parseReturnStmt() ast.Stmt {
 	pos := p.pos
 	p.expect(token.Return)
 
-	var x []ast.Expr
+	var x ast.Expr
 	if p.token != token.Semicolon && p.token != token.RBrace {
-		x = p.parseExprList()
+		x = p.parseExpr()
 	}
 	p.expectSemi()
 
 	return &ast.ReturnStmt{
 		ReturnPos: pos,
-		Results:   x,
+		Result:    x,
 	}
 }
 

compiler/parser/parser_test.go

@@ -144,8 +144,8 @@ func emptyStmt(implicit bool, pos source.Pos) *ast.EmptyStmt {
 	return &ast.EmptyStmt{Implicit: implicit, Semicolon: pos}
 }
 
-func returnStmt(pos source.Pos, results ...ast.Expr) *ast.ReturnStmt {
+func returnStmt(pos source.Pos, result ast.Expr) *ast.ReturnStmt {
-	return &ast.ReturnStmt{Results: results, ReturnPos: pos}
+	return &ast.ReturnStmt{Result: result, ReturnPos: pos}
 }
 
 func forStmt(init ast.Stmt, cond ast.Expr, post ast.Stmt, body *ast.BlockStmt, pos source.Pos) *ast.ForStmt {
@@ -309,7 +309,7 @@ func equalStmt(t *testing.T, expected, actual ast.Stmt) bool {
 			equalStmt(t, expected.Body, actual.(*ast.ForInStmt).Body) &&
 			assert.Equal(t, expected.ForPos, actual.(*ast.ForInStmt).ForPos)
 	case *ast.ReturnStmt:
-		return equalExprs(t, expected.Results, actual.(*ast.ReturnStmt).Results) &&
+		return equalExpr(t, expected.Result, actual.(*ast.ReturnStmt).Result) &&
 			assert.Equal(t, expected.ReturnPos, actual.(*ast.ReturnStmt).ReturnPos)
 	case *ast.BranchStmt:
 		return equalExpr(t, expected.Label, actual.(*ast.BranchStmt).Label) &&

docs/interoperability.md

@@ -62,7 +62,7 @@ func main() {
 	}
 
 	// run the compiled bytecode
-	// a compiled bytecode 'c' can be executed multiple without re-compiling it
+	// a compiled bytecode 'c' can be executed multiple times without re-compiling it
 	if err := c.Run(); err != nil {
 		panic(err)
 	}

docs/tengo-cli.md

@@ -10,6 +10,8 @@ To install `tengo` tool, run:
 go get github.com/d5/tengo/cmd/tengo
 ```
 
+Or, you can download the precompiled binaries from [here](https://github.com/d5/tengo/releases/latest). 
+
 ## Compiling and Executing Tengo Code
 
 You can directly execute the Tengo source code by running `tengo` tool with your Tengo source file (`*.tengo`).
@@ -21,8 +23,8 @@ tengo myapp.tengo
 Or, you can compile the code into a binary file and execute it later.
 
 ```bash
-tengo -c -o myapp myapp.tengo   # compile 'myapp.tengo' into binary file 'myapp'
+tengo -o myapp myapp.tengo   # compile 'myapp.tengo' into binary file 'myapp'
-tengo myapp                     # execute the compiled binary `myapp`	
+tengo myapp                  # execute the compiled binary `myapp`	
 ```
 
 ## Tengo REPL

runtime/vm.go

@@ -785,16 +785,6 @@ func (v *VM) Run() error {
 			}
 
 		case compiler.OpReturnValue:
-			//numRets := int(compiler.ReadUint8(v.curInsts[v.ip+1:]))
-			//_ = int64(compiler.ReadUint8(v.curInsts[v.ip+1:]))
-			v.ip++
-
-			// TODO: multi-value return is not fully implemented yet
-			//var rets []*objects.Object
-			//for i := 0; i < numRets; i++ {
-			//	val := v.pop()
-			//	rets = append(rets, val)
-			//}
 			retVal := v.stack[v.sp-1]
 			//v.sp--
 
@@ -808,11 +798,6 @@ func (v *VM) Run() error {
 			//v.sp = lastFrame.basePointer - 1
 			v.sp = lastFrame.basePointer
 
-			//for _, retVal := range rets {
-			//	if err := v.push(retVal); err != nil {
-			//		return err
-			//	}
-			//}
 			if v.sp-1 >= StackSize {
 				return ErrStackOverflow
 			}