Question

Just started learning Haskell.

I have an empty source file with this inside:

pe :: (Integral a) => a -> a
pe y = sum [x | x <- [1..y-1], x `mod` 3 == 0 || x `mod` 5 == 0]

Now if I ghci this, I can call pe like so:

*Main> pe 1000
233168

How do I call it from within my source file? If I have

pe 1000

it returns a cryptic error:

GHC stage restriction: `pe'
   is used in a top-level splice or annotation,
   and must be imported, not defined locally
 In the expression: pe 1000

Do I need to declare it in main or something?

Answer 1

Yes, you need to hook it up to your main function. For example,

main = print (pe 1000)

If you want to have multiple calls, you can combine them with do-notation:

main = do
    print (pe 500)
    print (pe 1000)