микрозадача

There exists exactly one Pythagorean triplet for which a + b + c = 1000. Find abc.

A Pythagorean triplet is a set of three natural numbers, a < b < c, for which, a^2 + b^2 = c^2

limit = 1000
result = head [
(prod, (x, y, z)) | x <- [1..limit], y <- [1..limit], 
let z = limit - x - y, z > 0, x*x + y*y == z*z, let prod = x*y*z
]