[Haskell-cafe] Newbie syntax question
André Vargas Abs da Cruz
andrev at ele.puc-rio.br
Fri Sep 16 15:18:03 EDT 2005
That's exactly what i was looking for. Thank you very much !!!
Cheers,
André
ChrisK wrote:
>There is the "flip" function which changes the order of the first 2
>parameters
>
>Prelude> :t flip
>flip :: forall c a b. (a -> b -> c) -> b -> a -> c
>
>So I think
>map ( (flip foo) 5 ) my_list_of_lists_of_doubles
>will work, as will using a lambda expression
>map (\x -> foo x 5) may_list_of_lists_of_doubles
>
>
>André Vargas Abs da Cruz wrote:
>
>
>>Hi,
>>
>> I have been using Haskell for a few weeks now and I can say that I am
>>totally impressed by how easy it is to program with it. I am now doing
>>some small exercises to get used to the language syntax and I have a
>>little (newbie) question:
>>
>> Suppose I declare a function foo like:
>>
>> foo :: [Double] -> Int -> Int
>> foo a b
>>
>> Suppose now that I want to apply this function to a list that
>>contains lists of doubles (something like [[Double]]) using map, but I
>>want to keep the 'b' parameter fixed (with a value of 5 for instance).
>>Is it possible to use map passing the function foo with the 2nd argument
>>only ? In other words, if I wrote this function like:
>>
>> foo :: Int -> [Double] -> Int
>>
>> I could clearly call it with:
>>
>> map (foo 5) my_list_of_lists_of_doubles
>>
>> But how to do that (if possible) when I invert the parameters list ?!
>>
>> Thanks in advance,
>> Andre Abs da Cruz
>>_______________________________________________
>>Haskell-Cafe mailing list
>>Haskell-Cafe at haskell.org
>>http://www.haskell.org/mailman/listinfo/haskell-cafe
>>
>>
>
>
>
>
--
-------------------------------------------------------
André Vargas Abs da Cruz
Laboratório de Inteligência Computacional Aplicada
Departamento de Engenharia Elétrica
Pontifícia Universidade Católica - Rio de Janeiro
http://www.ica.ele.puc-rio.br/
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