Or you can try foldr1, which doesn't need a terminating value.

Here's its definition from the Standard Prelude

foldr1                  :: (a -> a -> a) -> [a] -> a
foldr1 _ [x]            =  x
foldr1 f (x:xs)         =  f x (foldr1 f xs)
foldr1 _ []             =  errorEmptyList "foldr1"

On Mon, Mar 3, 2014 at 12:21 PM, Roelof Wobben <r.wobben@home.nl> wrote:

Thanks,

This did the job:

import Data.Char

x = foldr max 0 [5,10,2,8,1]

-- Note that comments are preceded by two hyphens
{- or enclosed
in curly brace/hypens pairs. -}
main = print x

Roelof

Emanuel Koczwara schreef op 2-3-2014 22:51:
Hi,

W dniu 02.03.2014 22:44, Roelof Wobben pisze:

Hello,

I now have to use foldr to find the max value in a list.

So I do this:

import Data.Char

x = foldr max [5,10,2,8.1]
-- Note that comments are preceded by two hyphens
{- or enclosed
in curly brace/hypens pairs. -}
main = print x

But now I see this error message:

main.hs@7:8-7:13
No instance for (Show ([[t0]] -> [t0])) arising from a use of `print' Possible fix: add an instance declaration for (Show ([[t0]] -> [t0])) In the expression: print x In an equation for `main': main = print x

Please look at foldr type and documentation. There is one argument missing in your code.

Regards,
Emanuel
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