(define reify-h (make-hash))
(define reflect-h (make-hash))
(define (reflect c) (hash-ref! reflect-h c (lambda () (define (f arg) (reflect `(,c ,(reify arg)))) (hash-set! reify-h f c) f)))
(define (reify f) (hash-ref reify-h f (lambda () (define formal (gensym)) `(lambda (,formal) ,(reify (f (reflect formal)))))))
(define (((S a) b) c) ((a c) (b c)))
(define ((K a) b) a)
(define (I a) a)
(define (((B a) b) c) (a (b c)))
(define ((((D a) b) c) d) ((a b) (c d)))
(reify ((((((S K) I) B) I) D) I))