Yes, sure (defvar *chip*) (defun memory (&optional (chip *chip*)) (chip-memory chip)) Just binding the variable is enough. If you want to hide

Yes, sure (defvar *chip*) (defun memory (&optional (chip *chip*)) (chip-memory chip)) Just binding the variable is enough. If you want to hide this variable as an implementation detail, you can use a macro: (defmacro with-chip (chip &body body) `(let ((*chip* ,chip)) ,@body)) You could also have a symbol-macrolet so that "memory" expands as a call, i.e. "(memory)", but then you would have the same syntax as the above poster wanted to avoid ;-) (except that accesseors already provide setf functions)