Add file operations

builtins/close.go

@@ -0,0 +1,27 @@
+package builtins
+
+import (
+	"monkey/object"
+	"monkey/typing"
+	"syscall"
+)
+
+// Close  ...
+func Close(args ...object.Object) object.Object {
+	if err := typing.Check(
+		"close", args,
+		typing.ExactArgs(1),
+		typing.WithTypes(object.INTEGER_OBJ),
+	); err != nil {
+		return newError(err.Error())
+	}
+
+	fd := int(args[0].(*object.Integer).Value)
+
+	err := syscall.Close(syscall.Handle(fd))
+	if err != nil {
+		return newError("IOError: %s", err)
+	}
+
+	return &object.Null{}
+}