most probably yes. I had the exact same question for: module Factors where import Prelude divides x y = (mod x y == 0) factors x = filter (divides x) [1..x] nonTrivialFactors x = filter (\y -> y /= 1 && y /= x) [1..x] isEmpty [] = True isEmpty _ = False -- isPrime = isEmpty . nonTrivialFactor -- says isPrime :: Integer -> Bool -- this one say isPrime :: (Integral a) => a -> Bool isPrime x = isEmpty (nonTrivialFactors x) frankly this is not desired, but I cannot see why it's particularly harmful. is it? note: I was devising this example mostly to show the usefulness of laziness ;) --- Neil Mitchell wrote:

I think this is the monomorphism restriction, you can see more details on the web page:

http://www.haskell.org/hawiki/MonomorphismRestriction

On 3/30/06, David Laffin wrote:

...

Hi,

Newbie question. Given the inferred type for

square,

...

the inferred types for quad1, quad2 and quad3 are what I would expect. Is there a straightforward explanation (i.e. one that a newbie would understand) as to why the inferred type for quad4 is less general?

Regards, dl

-- GHC Interactive, version 6.4, for Haskell 98.

Prelude> let square x = x * x Prelude> :t square square :: (Num a) => a -> a

Prelude> let quad1 x = square (square x) Prelude> :t quad1 quad1 :: (Num a) => a -> a

Prelude> let quad2 x = square $ square x Prelude> :t quad2 quad2 :: (Num a) => a -> a

Prelude> let quad3 x = (square . square) x Prelude> :t quad3 quad3 :: (Num a) => a -> a

Prelude> let quad4 = square . square Prelude> :t quad4 quad4 :: Integer -> Integer

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