Code style improvement

Haskell/p001.hs

@@ -1,11 +1,11 @@
 -- If we list all the natural numbers below 10 that are multiples of 3 or 5, we get 3, 5, 6 and 9. The sum of these multiples is 23.
 --
 -- Find the sum of all the multiples of 3 or 5 below 1000.
-sumMultiples :: (Integral n) => n
+
+sumMultiples :: Integer
 sumMultiples = sum(filter p [ n | n <- [1..999] ])
                 where p n = n `mod` 3 == 0 || n `mod` 5 == 0
 
-main :: IO ()
 main =  do
     let result = sumMultiples
     putStrLn $ "Project Euler, Problem 1\n"

Haskell/p002.hs

@@ -3,15 +3,15 @@
 -- 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, ...
 --
 -- By considering the terms in the Fibonacci sequence whose values do not exceed four million, find the sum of the even-valued terms.
-fib :: (Integral n) => n -> n
+
+fib :: Integer -> Integer
 fib 0 = 0
 fib 1 = 1
 fib n = fib (n-1) + fib(n-2)
 
-sumEvenFib :: (Integral n) => n
+sumEvenFib :: Integer
 sumEvenFib = sum $ filter even $ takeWhile (<=4000000) (map fib [0..])
 
-main :: IO ()
 main =  do
     let result = sumEvenFib
     putStrLn $ "Project Euler, Problem 2\n"

Haskell/p003.hs

@@ -1,14 +1,14 @@
 -- The prime factors of 13195 are 5, 7, 13 and 29.  --
 -- What is the largest prime factor of the number 600851475143?
-import ProjectEuler
 
-maxPrimeFactor :: (Integral n) => n -> n
+import ProjectEuler (isPrime)
+
+maxPrimeFactor :: Integer -> Integer
 maxPrimeFactor n
     | isPrime n         = n         
-    | n `mod` 2 == 0    = maxPrimeFactor $ fromIntegral n `div` 2
-    | otherwise         = maxPrimeFactor $ fromIntegral n `div` head [i | i <- [3,5..], n `mod` i == 0 && isPrime i]
+    | n `mod` 2 == 0    = maxPrimeFactor $ n `div` 2
+    | otherwise         = maxPrimeFactor $ n `div` head [i | i <- [3,5..], n `mod` i == 0 && isPrime i]
 
-main :: IO ()
 main = do
     let result = maxPrimeFactor 600851475143
     putStrLn $ "Project Euler, Problem 3\n"