SEND + MORE = MONEY

send.scm

;; gosh> (gauche-version)
;; "0.9.5"
;; egison.scm は https://github.com/egison/egison-scheme/blob/master/egison.scm
;; から取得し、モジュール化しておく
;; > (add-load-path "./send")
;; > (use send)
;; リロード時 > (reload 'send)


;; モジュールのインタフェースの定義
(define-module send
  (use egison)
  (export
    test1
    test2
    send1
    send2
  )
)

;; モジュール本体
(select-module send)

(define test1
  (match-all '(1 2 5 9 4) (Multiset Integer) [(cons x (cons `(+ x 1) _)) x]) ; (1 4)
)
(define test2
  (match-all '(1 2 5 9 4) (Multiset Integer) [(cons (and x (pred (lambda (y) (= y 4)))) _) x]) ; (4)
)


(define (money1? xs)
  (let
    ( (s (list-ref xs 0))
      (e (list-ref xs 1))
      (n (list-ref xs 2))
      (d (list-ref xs 3))
      (o (list-ref xs 4))
      (r (list-ref xs 5))
      (y (list-ref xs 6)) )
    (=
      (+ (+ (* 1000 s) (* 100 e) (* 10 n) d) (+ 1000 (* 100 o) (* 10 r) e))
      (+ 10000 (* 1000 o) (* 100 n) (* 10 e) y)
    )
  )
)

;; 解を返す：((9 5 6 7 0 8 2))
(define send1
  (filter money1?
    (match-all '(0 2 3 4 5 6 7 8 9) (Multiset Integer)
      [(cons (and s (not `0)) (cons e (cons n (cons d (cons o (cons r (cons y _))))))) (list s e n d o r y)]
    )
  )
)

(define (money2? s e n d o r)
  (lambda (y)
    (=
      (+ (+ (* 1000 s) (* 100 e) (* 10 n) d) (+ 1000 (* 100 o) (* 10 r) e))
      (+ 10000 (* 1000 o) (* 100 n) (* 10 e) y)
    )
  )
)

;; 解を返す：((9 5 6 7 0 8 2))
(define send2
  (match-all '(0 2 3 4 5 6 7 8 9) (Multiset Integer)
    [(cons (and s (not `0)) (cons e (cons n (cons d (cons o (cons r
      (cons (and y (pred (money2? s e n d o r))) _))))))) (list s e n d o r y)]
  )
)


(provide "send")