Gauche > Archives > 2014/11/24

; tee structure
(define (left-tee  x y z) (cons (cons x y) z)  )
(define (right-tee x y z) (cons x (cons y z) ) )

(define (%tee? op t) (and (pair? t) ($ pair? $ op t) ) )
(define left-tee?  (pa$ %tee? car) )
(define right-tee? (pa$ %tee? cdr) )
(define tee? (any-pred left-tee? right-tee?) )
(define dual-tee? (every-pred left-tee? right-tee?) )