restructure project

internal/builtins/int.go

@@ -0,0 +1,35 @@
+package builtins
+
+import (
+	"monkey/internal/object"
+	"monkey/internal/typing"
+	"strconv"
+)
+
+// Int ...
+func Int(args ...object.Object) object.Object {
+	if err := typing.Check(
+		"int", args,
+		typing.ExactArgs(1),
+	); err != nil {
+		return newError(err.Error())
+	}
+
+	switch arg := args[0].(type) {
+	case *object.Boolean:
+		if arg.Value {
+			return &object.Integer{Value: 1}
+		}
+		return &object.Integer{Value: 0}
+	case *object.Integer:
+		return arg
+	case *object.String:
+		n, err := strconv.ParseInt(arg.Value, 10, 64)
+		if err != nil {
+			return newError("could not parse string to int: %s", err)
+		}
+		return &object.Integer{Value: n}
+	default:
+		return &object.Integer{}
+	}
+}