[Haskell-cafe] Newbie syntax question

ChrisK chrisk at MIT.EDU
Fri Sep 16 15:04:51 EDT 2005

There is the "flip" function which changes the order of the first 2

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
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