more builtins

builtins/oct.go

@@ -0,0 +1,20 @@
+package builtins
+
+import (
+	"fmt"
+	"monkey/object"
+	"strconv"
+)
+
+// Oct ...
+func Oct(args ...object.Object) object.Object {
+	if len(args) != 1 {
+		return newError("wrong number of arguments. got=%d, want=1",
+			len(args))
+	}
+
+	if i, ok := args[0].(*object.Integer); ok {
+		return &object.String{Value: fmt.Sprintf("0%s", strconv.FormatInt(i.Value, 8))}
+	}
+	return newError("argument to `oct` not supported, got %s", args[0].Type())
+}