[Haskell-cafe] Call for discussion: OverloadedLists extension

[Paul Visschers]

Would that also work for vectors that have their length in their type? And
while we are at it, how about overloaded tuples?

Paul

On Mon, Sep 24, 2012 at 7:19 PM, Simon Peyton-Jones
<simonpj at microsoft.com>wrote:

> |  I remember a similar discussion a few years ago. The question of whether
> |  or not overloading list literals a good idea notwithstanding, the
> problem
> |  with this is that fromList for vectors is highly inefficient. So if
> |  something like this gets implemented and if vector/array literals are
> one
> |  of the main motivations then I really hope there will be no lists
> |  involved.
>
> Would you like to remind us why it is so inefficient?  Can't the vector
> construction be a fold over the list?  Ah... you need to know the *length*
> of the list, don't you?  So that you can allocate a suitably-sized vector.
>  Which of course we do for literal lists.
>
> So what if fromList went
>         fromList :: Int -> [b] -> a b
> where the Int is the length of the list?
>
> Simon
>
>
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