You'll find in the Prelude that Int is an instance of Bounded, so minBound and maxBound are defined, and are the identities you need.

cheers

-----Original Message-----
From: sashan [mailto:sashang@ihug.co.nz]
Sent: Monday, May 05, 2003 12:30 PM
To: haskell-cafe@haskell.org
Subject: Maximum value in a list

Hi

I was reading through the tutorial Yet Another Haskell Tutorial and
doing chapter 3 ex 5, write a function using foldr and max to return the
maximum value in a list.

I came up with the following that will work for positive numbers.

maxInList :: [Int]->Int
maxInList [] = 0
maxInList l = foldr max 0 l

Is there an identity for the max function? Because currently if the list
  [-1,-3,-4] is passed to maxInList it will return 0.

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