Re: [Haskell-cafe] Data.Tree.Zipper in the standard libraries

On 2008 May 23, at 13:34, Luke Palmer wrote:

On Fri, May 23, 2008 at 10:55 AM, Jules Bean wrote:

...

Krasimir Angelov wrote:

...

The monads design is used in Data.Map i.e.

lookup :: (Monad m, Ord k) => k -> Map k a -> m a

which is widely considered a poor design decision and a wart on Data.Map.

It is? Can you point to somewhere explaining that? I rather liked that idiom.

I'd argue that the poor design decision was killing MonadZero, and the type of Data.Map.lookup is a hackaround. -- brandon s. allbery [solaris,freebsd,perl,pugs,haskell] allbery@kf8nh.com system administrator [openafs,heimdal,too many hats] allbery@ece.cmu.edu electrical and computer engineering, carnegie mellon university KF8NH