[Haskell-beginners] list doesn't end

Hi, I am doing some further learning with euler now in Haskell instead of Julia. But I am getting something strange. [x+y+z | x <- a2, y <- b3,  z <- c4, (x+y+z) < 50] a2, b3, c4 are all finite lists derived from the lazy list of the primes package. the output is: [28,47,33,49 this is not a typo it is still calculating hence the missing bracket (for the last couple of hours, when to a christmas fair in between). The only thing is that, this should be the answer: [28,47,33,49]  so it should be done but its not. what am I doing wrong? best,