Script to find triangular numbers that are simultaneously square numbers.

squaretri.hs

squares :: (Integral a) => [a]
squares = map (\x -> x*x) [1..]

triangles :: (Integral a) => [a]
triangles = map (\x -> (div (x*(x+1)) 2)) [1..]

match :: (Integral a) => [a] -> [a] -> [a]
match (a:as) (b:bs)
    | a == b = a:(match as bs)
    | a < b = match (dropWhile ((>) b ) as) (b:bs)
    | otherwise = match (a:as) (dropWhile ((>) a) bs)

main :: IO ()
main = mapM_ (putStrLn.show) (match squares triangles)