Re: [Haskell-beginners] MaximumBy

Hi, if it is ok for you to work only with lists (not generic foldables), you could write it this way: maximumBy cmp [x] = x maximumBy cmp (x:y:xs) = if (cmp x y)==GT then maximumBy cmp (x:xs) else maximumBy cmp (y:xs) the signature is maximumBy :: (a -> a -> Ordering) -> [a] -> a Ut http://www.avg.com/email-signature?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=webmail Mail priva di virus. www.avg.com http://www.avg.com/email-signature?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=webmail <#m_-9203042563784922724_DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2> Il giorno ven 22 mag 2020 alle ore 20:53 Alexander Chen < alexander@chenjia.nl> ha scritto:

Hi,

maximumBy :: Foldable t => (a -> a -> Ordering) -> t a -> a

its in the Data.List

May 22, 2020 8:33:33 PM CEST "Daniel van de Ghinste (Lord_Luvat)" < danielvandeghinste@gmail.com> wrote:

Hi,

Maybe I’m on a different version, but I don’t see a function called maximumBy in my base Prelude. Can you give us a type signature for the function? If you’re not sure how to do that just type: Prelude> :t maximumBy In your ghci interpreter and it should return the type signature of whatever you have after ‘:t ‘ (this works for compound expressions too if you put them in brackets)

Perhaps maximumBy is what you’re meant to call your rewrite of the existing function I see called ‘maximum’ (seems to do the same thing). Let me know if thats the case and I can explain how it works.

Best regards, Daniel van de Ghinste

On 22 May 2020, at 20:20, Alexander Chen wrote:

Hi,

I want to re-write a function maximumBy (its an assignment).

However, I don't get how it works.

...

maximumBy compare [1,53,9001, 10] 9001

but what does it actually do to get there?

thanks in advance.

best,

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