haskell: add p1, p2

Signed-off-by: Amneesh Singh <natto@weirdnatto.in>

haskell/Lib.hs

@@ -1 +1,4 @@
 module Lib where
+
+fib :: [ Integer ]
+fib = 1 : 2 : zipWith (+) fib (tail fib)

haskell/p1.hs

@@ -0,0 +1,5 @@
+main :: IO ()
+main = putStr $ show solve
+
+solve :: Integer
+solve = sum [ x | x <- [0..999], mod x 3 == 0 || mod x 5 == 0 ]

haskell/p2.hs

@@ -0,0 +1,7 @@
+import Lib (fib)
+
+main :: IO ()
+main = putStr $ show solve
+
+solve :: Integer
+solve = sum $ filter even $ takeWhile (<= 4000000) fib