+ (cond
+ (binding (apply binding args))
+ ((every-type-translateable-p (cons return-type arg-types))
+ (setq binding (apply #'mkbinding name return-type arg-types))
+ (apply binding args))
+ (t
+ (dolist (type-spec (cons return-type arg-types))
+ (unless (type-translateable-p type-spec)
+ (error "Can't translate type ~A" type-spec)))))))))