Add Haskell solutions for Problems 9, 10

Haskell/p009.hs

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+-- A Pythagorean triplet is a set of three natural numbers, a < b < c, for which,
+--
+-- a2 + b2 = c2
+--
+-- For example, 32 + 42 = 9 + 16 = 25 = 52.
+--
+-- There exists exactly one Pythagorean triplet for which a + b + c = 1000.
+--
+-- Find the product abc.
+
+pythagoreanTriplet :: (Integral a) => a -> (a, a, a)
+pythagoreanTriplet n = head [ (x, y, z) | x <- [1..n], y <- [1..n], z <- [1..n], x + y + z == n, x^2 + y^2 == z^2]
+
+prodTriplet :: (Integral a) => (a, a, a) -> a
+prodTriplet (x, y, z) = x * y * z
+
+main = do
+    let result = prodTriplet $ pythagoreanTriplet 1000
+    putStrLn $ "Project Euler, Problem 9\n"
+        ++ "Answer: " ++ (show result)

Haskell/p010.hs

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+-- The sum of the primes below 10 is 2 + 3 + 5 + 7 = 17.
+--
+-- Find the sum of all the primes below two million.
+
+import ProjectEuler (isPrime)
+
+sumPrimes :: (Integral a) => a -> a
+sumPrimes n = sum [ x | x <- [1..n], isPrime(x) ]
+
+main = do
+    let result = sumPrimes 2000000
+    putStrLn $ "Project Euler, Problem 10\n"
+        ++ "Answer: " ++ (show result)