Roman number and a root of a number in Haskell

binary_search/root_of_a_number.hs

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+
+sqrtInt :: Int -> Int
+sqrtInt x = sqrtInt' x 0 x
+         where sqrtInt' :: Int -> Int -> Int -> Int
+               sqrtInt' x low high
+                   | low >= high    = low
+                   | middSq < x  = sqrtInt' x (midd+1) high
+                   | middSq > x  = sqrtInt' x (low) (midd-1)
+                   | middSq == x = midd
+                 where midd   = (high + low) `quot` 2
+                       middSq = midd*midd
+

roman/roman.hs

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+module Main where
+
+import Data.Bool
+
+romanToInt :: Char -> Integer
+romanToInt 'I' = 1
+romanToInt 'V' = 5
+romanToInt 'X' = 10
+romanToInt 'L' = 50
+romanToInt 'C' = 100
+romanToInt 'D' = 500
+romanToInt 'M' = 1000
+romanToInt  _  = 0
+
+
+romanToNum :: [Char] -> Integer
+romanToNum xs
+   | length xs == 0 = 0
+   | length xs == 1 = romanToInt (head xs)
+   | otherwise      = let fst = romanToInt (head xs)
+                          snd = romanToInt (xs  !! 1)
+                          t1  = romanToNum (tail xs)
+                      in if fst < snd then t1 - fst
+                                      else t1 + fst
+
+main :: IO()
+main = putStrLn result
+
+result :: [Char]
+result = if final == False then "Your program is wrong"
+                         else "Your program is working!!! "
+  where final = foldl (&&) True expr
+        expr :: [Bool]
+        expr = [e1, e2, e3, e4, e5]
+        e1   = (romanToNum "XVI") == 16
+        e2   = (romanToNum "VI") == 6
+        e3   = (romanToNum "CM") == 900
+        e4   = (romanToNum "CMXL") == 940
+        e5   = (romanToNum "XIII") == 13
+