Add Haskell solution for Problem 34

Haskell/p034.hs

@@ -0,0 +1,23 @@
+-- 145 is a curious number, as 1! + 4! + 5! = 1 + 24 + 120 = 145.
+--
+-- Find the sum of all numbers which are equal to the sum of the factorial of their digits.
+--
+-- Note: as 1! = 1 and 2! = 2 are not sums they are not included.
+
+import Data.Char
+
+factorial :: (Integral a) => a -> a
+factorial 0 = 1
+factorial n = n * factorial (n - 1)
+
+factDigits :: [Int]
+factDigits = map factorial [0..9]
+
+equalsDigitFactorial :: Int -> Bool
+equalsDigitFactorial n = let fact_digit_sum = sum $ [ factDigits !! x | x <- map digitToInt (show n) ]
+                         in fact_digit_sum == n
+
+main = do
+    let result = sum $ filter equalsDigitFactorial [10..9999999]
+    putStrLn $ "Project Euler, Problem 34\n"
+        ++ "Answer: " ++ show result