Re: [Haskell-cafe] a minor bug (memory leak) in ListLike package

Hi, I think 3 < genericLength [1..] should fail, that laziness is not we want. I can not derive ListLike instance using GHC extensions, can you provide a working example? Thanks On Tue, Aug 23, 2011 at 9:47 PM, Ivan Lazar Miljenovic < ivan.miljenovic@gmail.com> wrote:

On 24 August 2011 11:10, bob zhang wrote:

...

Hi, John, there is a space leak problem in ListLike typeclass, in the method genericLength calclen !accum cl = calclen accum cl =

I _think_ this may cause problems with some data types (e.g.

http://hackage.haskell.org/packages/archive/numbers/2009.8.9/doc/html/Data-N... ) that require the extra laziness (that is, you can do things like ` 3 < genericLength [1..] ' and have it return True).

...

--- thank you for your nice library btw, is there any way to derive ListLike interface automatically? for such type : newtype List a = List {[a]}

GeneralizedNewtypeDeriving can do that.

-- Ivan Lazar Miljenovic Ivan.Miljenovic@gmail.com IvanMiljenovic.wordpress.com

-- Best, bob