;; given this C code:

typedef enum {
    val1,
    val2,
    val3
} some_enum;


;; this compiles:

(define-foreign-type some-enum "some_enum")

;; this does not compile:

(define-foreign-enum-type (some-enum "some_enum")
 (some-enum->int int->some-enum)
 val1 val2 val3)