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

On Mon, Dec 29, 2008 at 4:48 AM, Ryan Ingram wrote:

On Sun, Dec 28, 2008 at 10:13 PM, David Menendez 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 http://www.eyrie.org/~zednenem/