SEND + MORE = MONEY

it.hs

import Data.List     (permutations)
import Control.Monad (guard)

main = putStrLn $ head solutions

solutions = do
  let range = [0.. 9]

  [s,e,n,d,m,o,r,y,_,_] <- permutations range
  
  let a = fromDigits   [s,e,n,d]
      b = fromDigits   [m,o,r,e]
      c = fromDigits [m,o,n,e,y]
  
  guard $ m == 1
  guard $ a + b == c
  
  return $ unwords [show a, "+", show b, "=", show c]
  
fromDigits = foldl (\a b -> a * 10 + b) 0

it.prolog

:- use_module(library(lists)).

solve(A + B = C) :-
    permutation([0,2,3,4,5,6,7,8,9], [S,E,N,D,O,R,Y | _]),
    M  = 1,
    S \= 0,
    fromDigits(  [S,E,N,D], A),
    fromDigits(  [M,O,R,E], B),
    fromDigits([M,O,N,E,Y], C),
    C is A + B.

fromDigits(List, Result) :-
    foldl(attach, List, 0, Result).

attach(A, B, C) :- C is B * 10 + A.