int() bool() and str()

object/builtin_bool.go

@@ -0,0 +1,38 @@
+package object
+
+// Bool ...
+func Bool(args ...Object) Object {
+	if len(args) != 1 {
+		return newError("wrong number of arguments. got=%d, want=1", len(args))
+	}
+
+	switch arg := args[0].(type) {
+	case *Null:
+		return &Boolean{Value: false}
+	case *Boolean:
+		return arg
+	case *Integer:
+		if arg.Value == 0 {
+			return &Boolean{Value: false}
+		}
+		return &Boolean{Value: true}
+	case *String:
+		if len(arg.Value) > 0 {
+			return &Boolean{Value: true}
+		}
+		return &Boolean{Value: false}
+	case *Array:
+		if len(arg.Elements) > 0 {
+			return &Boolean{Value: true}
+		}
+		return &Boolean{Value: false}
+	case *Hash:
+		if len(arg.Pairs) > 0 {
+			return &Boolean{Value: true}
+		}
+		return &Boolean{Value: false}
+
+	default:
+		return newError("argument to `bool` not supported, got=%s", args[0].Type())
+	}
+}

object/builtin_int.go

@@ -0,0 +1,29 @@
+package object
+
+import "strconv"
+
+// Int ...
+func Int(args ...Object) Object {
+	if len(args) != 1 {
+		return newError("wrong number of arguments. got=%d, want=1", len(args))
+	}
+
+	switch arg := args[0].(type) {
+	case *Boolean:
+		if arg.Value {
+			return &Integer{Value: 1}
+		}
+		return &Integer{Value: 0}
+	case *Integer:
+		return arg
+	case *String:
+		n, err := strconv.ParseInt(arg.Value, 10, 64)
+		if err != nil {
+			return newError("could not parse string to int: %s", err)
+		}
+
+		return &Integer{Value: n}
+	default:
+		return newError("argument to `int` not supported, got=%s", args[0].Type())
+	}
+}

object/builtin_str.go

@@ -0,0 +1,19 @@
+package object
+
+import (
+	"fmt"
+)
+
+// Str ...
+func Str(args ...Object) Object {
+	if len(args) != 1 {
+		return newError("wrong number of arguments. got=%d, want=1", len(args))
+	}
+
+	arg, ok := args[0].(fmt.Stringer)
+	if !ok {
+		return newError("argument to `str` not supported, got %s", args[0].Type())
+	}
+
+	return &String{Value: arg.String()}
+}

object/builtins.go

@@ -17,6 +17,9 @@ var Builtins = map[string]*Builtin{
 	"pop":    {Name: "pop", Fn: Pop},
 	"exit":   {Name: "exit", Fn: Exit},
 	"assert": {Name: "assert", Fn: Assert},
+	"bool":   {Name: "bool", Fn: Bool},
+	"int":    {Name: "int", Fn: Int},
+	"str":    {Name: "str", Fn: Str},
 }
 
 // BuiltinsIndex ...