Send more cpu cycles!

sendMoreMoney.clj

(ns learn-logic.core)

(use 'clojure.core.logic)

; an attempt to solve the classic "Send more money" problem, where
;    S E N D
; +  M O R E
; ----------
;  M O N E Y
;
; and both S and M cannot be 0

; A very inefficient way to turn a list of numerals into a number
(defn digits-numbero [nums total]
  (fresh [n1 ns]
    (conso n1 ns nums)
    (conde 
      ((emptyo ns) (== n1 total))
      ((fresh [n2 nr carry sum newNs]
        (conso n2 nr ns)
        (*fd n1 10 carry)
        (+fd carry n2 sum)
        (conso sum nr newNs)
        (digits-numbero newNs total))))))

; An attempt to write the solution straightforwardly in terms of the puzzle definition.
(defn -main []
  (run 1 [send more]
    (fresh [s e n d m o r y money]
      (infd s e n d m o r y (interval 0 9))
      (distincto [s e n d m o r y])
      (!=fd s 0)
      (!=fd m 0)
      (digits-numbero (list s e n d) send)
      (digits-numbero (list m o r e) more)
      (digits-numbero (list m o n e y) money)
      (+fd send more money))))
    
; Running this results in OutOfMemoryError.
; I further tried adding:
;      (<fd send 10000)
;      (<fd more 10000)
;      (<fd money 100000)
; With the same result.