misc fixes

bench.sh

@@ -0,0 +1,9 @@
+#!/usr/bin/env bash
+
+currentBranch="$(git branch --show-current)"
+
+hyperfine \
+  -w 5 \
+  -p "make build" \
+  -n "$currentBranch" \
+  './monkey examples/fib.monkey'

examples/fibi.monkey

@@ -15,4 +15,10 @@ fib := fn(n) {
    return a
 }
 
-print(fib(35))
+N := 35
+
+if (len(args()) > 0) {
+  N = int(args()[0])
+}
+
+print(fib(N))

examples/fibt.monkey

@@ -8,4 +8,10 @@ fib := fn(n, a, b) {
   return fib(n - 1, b, a + b)
 }
 
-print(fib(35, 0, 1))
+N := 35
+
+if (len(args()) > 0) {
+  N = int(args()[0])
+}
+
+print(fib(N, 0, 1))

internal/object/errors.go

@@ -18,3 +18,17 @@ func (e BinaryOpError) Error() string {
 func NewBinaryOpError(left, right Object, op string) BinaryOpError {
 	return BinaryOpError{left, right, op}
 }
+
+// DivisionByZeroError is an error returned when dividing by zero
+type DivisionByZeroError struct {
+	left Object
+}
+
+func (e DivisionByZeroError) Error() string {
+	return fmt.Sprintf("cannot divide %s by zero", e.left)
+}
+
+// NewDivisionByZeroError returns a new DivisionByZeroError
+func NewDivisionByZeroError(left Object) DivisionByZeroError {
+	return DivisionByZeroError{left}
+}

internal/object/int.go

@@ -65,6 +65,9 @@ func (i Integer) Mul(other Object) (Object, error) {
 func (i Integer) Div(other Object) (Object, error) {
 	switch obj := other.(type) {
 	case Integer:
+		if obj.Value == 0 {
+			return nil, NewDivisionByZeroError(i)
+		}
 		return Integer{i.Value / obj.Value}, nil
 	default:
 		return nil, NewBinaryOpError(i, other, "/")

internal/vm/vm.go

@@ -130,11 +130,19 @@ func (vm *VM) currentFrame() *Frame {
 }
 
 func (vm *VM) pushFrame(f Frame) {
+	if vm.fp >= MaxFrames {
+		panic("frame overflow")
+	}
+
 	vm.frames[vm.fp] = f
 	vm.fp++
 }
 
 func (vm *VM) popFrame() Frame {
+	if vm.fp == 0 {
+		panic("fame underflow")
+	}
+
 	vm.fp--
 	return vm.frames[vm.fp]
 }
@@ -201,6 +209,10 @@ func (vm *VM) push(o object.Object) error {
 }
 
 func (vm *VM) pop() object.Object {
+	if vm.sp == 0 {
+		panic("stack underflow")
+	}
+
 	o := vm.stack[vm.sp-1]
 	vm.sp--
 	return o
@@ -768,20 +780,22 @@ func (vm *VM) Run() (err error) {
 	if vm.Debug {
 		start := time.Now()
 		defer func() {
+			end := time.Now().Sub(start)
 			total := 0
 			opcodes := make([]code.Opcode, 0, len(opcodeFreqs))
 
-			for opcode := range opcodeFreqs {
+			for opcode, count := range opcodeFreqs {
 				opcodes = append(opcodes, opcode)
+				total += count
 			}
 
 			sort.SliceStable(opcodes, func(i, j int) bool {
 				return opcodeFreqs[opcodes[i]] > opcodeFreqs[opcodes[j]]
 			})
 
-			log.Printf("%d instructions executed in %s", total, time.Now().Sub(start))
-			log.Print("Top 10 instructions:")
-			for _, opcode := range opcodes[:10] {
+			log.Printf("%d instructions executed in %s %d/µs", total, end, total/int(end.Microseconds()))
+			log.Print("Top Instructions:")
+			for _, opcode := range opcodes[:min(len(opcodes), 10)] {
 				log.Printf("%10d %s", opcodeFreqs[opcode], opcode)
 			}
 		}()

monkey.go

@@ -81,12 +81,15 @@ func ExecFileVM(f string, args []string, debug, trace bool) (err error) {
 	} else {
 		bytecode, err = compile(f, debug)
 	}
-
 	if err != nil {
 		fmt.Println(err)
 		return
 	}
 
+	if debug {
+		log.Printf("Bytecode:\n%s\n", bytecode)
+	}
+
 	mvm := vm.New(f, bytecode)
 	mvm.Debug = debug
 	mvm.Trace = trace

repl.go

@@ -30,13 +30,20 @@ func VmREPL(args []string, debug, trace bool) error {
 		fmt.Println(err)
 		return fmt.Errorf("error opening terminal: %w", err)
 	}
-	defer term.Restore(0, initState)
+	defer func() {
+		if err := recover(); err != nil {
+			log.Printf("recovered from panic: %s", err)
+		}
+		term.Restore(0, initState)
+	}()
 	atexit.Register(func() {
 		term.Restore(0, initState)
 	})
 
 	t := term.NewTerminal(os.Stdin, ">>> ")
 	t.AutoCompleteCallback = autoComplete
+
+	object.Args = args
 	object.Stdout = t
 	object.ExitFunction = atexit.Exit
 
@@ -71,6 +78,10 @@ func VmREPL(args []string, debug, trace bool) error {
 			continue
 		}
 
+		if debug {
+			log.Printf("Bytecode:\n%s\n", c.Bytecode())
+		}
+
 		mvm := vm.NewWithState("<stdin>", c.Bytecode(), state)
 		mvm.Debug = debug
 		mvm.Trace = trace
@@ -80,7 +91,7 @@ func VmREPL(args []string, debug, trace bool) error {
 			continue
 		}
 
-		if val := mvm.LastPoppedStackElem(); val.Type() != object.NullType {
+		if val := mvm.LastPoppedStackElem(); val != nil && val.Type() != object.NullType {
 			fmt.Fprintln(t, val.Inspect())
 		}
 	}
@@ -137,7 +148,18 @@ func SimpleVmREPL(args []string, debug, trace bool) {
 		reader = bufio.NewReader(os.Stdin)
 	)
 
+	defer func() {
+		if err := recover(); err != nil {
+			log.Printf("recovered from panic: %s", err)
+		}
+	}()
+
+	t := term.NewTerminal(os.Stdin, ">>> ")
+	t.AutoCompleteCallback = autoComplete
+
 	object.Args = args
+	object.Stdout = t
+	object.ExitFunction = atexit.Exit
 
 	PrintVersionInfo(os.Stdout)
 	for {
@@ -171,6 +193,10 @@ func SimpleVmREPL(args []string, debug, trace bool) {
 			continue
 		}
 
+		if debug {
+			log.Printf("Bytecode:\n%s\n", c.Bytecode())
+		}
+
 		mvm := vm.NewWithState("<stdin>", c.Bytecode(), state)
 		mvm.Debug = debug
 		mvm.Trace = trace
@@ -180,7 +206,7 @@ func SimpleVmREPL(args []string, debug, trace bool) {
 			continue
 		}
 
-		if val := mvm.LastPoppedStackElem(); val.Type() != object.NullType {
+		if val := mvm.LastPoppedStackElem(); val != nil && val.Type() != object.NullType {
 			fmt.Println(val.Inspect())
 		}
 	}