Re: Efficent lens operation for Data.Map et al.

On Tue, 17 Jan 2012, Johan Tibell wrote:

On Tue, Jan 17, 2012 at 11:22 AM, wrote:

...

In fact, every other Map update operation should be derivable from the lens function.

We tried this an performance was terrible (although we used a zipper.)

Ah, sorry I misread your message the first time around. Ya, I don't mean to imply that every other operation should be derived from the lens function, just that, in principle, they could be. It would be interesting to compare how fast a lens based implemenation would be. (To be really fast, we probably want to CPS transform the store comonad so we don't have to decompose and recompose the resulting pair all the time.) But regardless, I want my fast lens primitive. :) -- Russell O'Connor http://r6.ca/ ``All talk about `theft,''' the general counsel of the American Graphophone Company wrote, ``is the merest claptrap, for there exists no property in ideas musical, literary or artistic, except as defined by statute.''