I want to get a random prime from a prime array name "primes". So I want to generate a random integer first, and then get the prime at that Integer position.

Here is my code:

```
getPrime :: IO Integer
getPrime =  do 
        pos <- getStdRandom (randomR (10, 100))
        return (primes !! pos)

```

(`primes` already exists and works well.) 

But when I load this code, it says "parse error on input `return'" 

Can anyone help me about this? Thx!!!!!!!!!!!!!!!