[Haskell-beginners] Re: [Haskell-cafe] represent data sturcture using function

[David Menendez]

On Mon, Dec 29, 2008 at 4:48 AM, Ryan Ingram <ryani.spam at gmail.com> wrote:
> On Sun, Dec 28, 2008 at 10:13 PM, David Menendez <dave at zednenem.com> wrote:
>> Here's the simplest way:
>>
>>    update k v map = \k' -> if k' == k then v else map k'

> Of course this version of update leaks crazy amounts of memory:
>
>> let bigmap = iterate (update Male 150) classA !! 100000
>> bigmap Male
>
> "bigmap" leaves a huge chain of thunks pointing at each other, which
> can never be freed.

Sure. It's slow, too. If you want a map that you can update, you're
usually much better off with a concrete data structure.

-- 
Dave Menendez <dave at zednenem.com>
<http://www.eyrie.org/~zednenem/>