You could always do something like this: isPrime :: Int -> Bool isPrime n = if (n < 2) then False else if (length (divisors n)) == 2 then True else False If the number is prime, you will only have two divisors, 1 and the number, so you know it isn't prime if you don't have two divisors. Also, primes are defined as being > 1, so it's good to put that check in as well. Mark Alex Teslin wrote:

Hi, I am a newbie in Haskell and have a trivial question.

I am using Simon Thomson's textbook for learning Haskell with Hugs. I am stack with exer 5.10, which asks to define isPrime function using divisors function previously defined.

I have managed to define the divisor function like this:

divisors :: Int -> [Int] divisors n = [x | x<-[1..n], n `mod` x == 0]

but when i am trying with isPrime function using divisors and list comprehension - i am lost because the type signature should be isPrime :: Int->Bool

But any list comprehension generates a list, which is not what i want.

Any suggestions please?

Thank you

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