Re: [Haskell-beginners] Function to compute the mean

Thank Tarik

Both are the same, Discard my previous mail 

Bur surely they are not both the same, as I indicated in my initial email ? Is it not the case that mean1 is a parametrically polymorphic functiion, while mean is a simple function ?  My question is about the relative advantages and disadvantes of each Thanks again J On Saturday, May 8, 2021, 02:12:26 PM GMT+1, Tarik ÖZKANLI wrote: No sorry, Both are the same, Discard my previous mail  Regards. Tarık On Sat, 8 May 2021 at 16:07, Tarik ÖZKANLI wrote:

Hello,

In standard usage there is not much difference. But in Haskell, people prefer to write in curried form (first implementation of yours) which has the advantage of using partially applied form when suitable.

Regards.

Tarık Özkanlı

On Sat, 8 May 2021 at 12:43, Joe King wrote:

...

Greeetings I am new here and pretty new to Haskell.

I was wondering what are the relative advanatges/disadvatnages of specifying a mean function in these two ways:

mean :: [Double] -> Double mean xs = sum xs / fromIntegral (length xs)

and

mean1 :: (Real a, Fractional b) => [a] -> b mean1 xs = realToFrac (sum xs) / genericLength xs

I understand that mean1 has the advantage that it can be called with lists of any Real type, so would work with things like 

foo :: [Int] foo = [1,2,3]

mean foo -- type mismatch error

mean1 foo -- no error

But suppose that I know I will only ever use lists of Double, is there still any advantage (or disadvantage of using mean1). For example is there any performance benefit by using mean in that case since mean1 has additional function evaluation. 

Are there any other considerations ?

Thanks in advance JK _______________________________________________ Beginners mailing list Beginners@haskell.org http://mail.haskell.org/cgi-bin/mailman/listinfo/beginners

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