How does this relate to the Maybe lenses in fclabels [1]? Erik
[1] http://hackage.haskell.org/packages/archive/fclabels/1.0.4/doc/html/Data-Label-Maybe.html On Wed, Dec 21, 2011 at 04:54, <rocon...@theorem.ca> wrote: > Do you miss null references from your old imperative programming days? Wish > that the worlds best imperative language had null references? Now your > wishes have come true with the new partial-lens package! > > partial-lens augment edwardk's data-lens package with partial lens. Partial > lenses are like regular lenses but have the possibility of not referencing > anything. In other words, null references are possible. One notable > different with null references from this package is that you can set them > without getting a run-time error. Instead setting a null reference is a > no-op; however it is possible to determine if setting failed from the return > value of the assignment operation. > > Actually I don't have any applications for partial lenses myself, so if you > find this library useful, please let me know. I wrote this mostly because > we know what partial lenses are in theory (they are the coalgebras of the > (Identity :+: Store b) comonad) but I wanted to see what a real library > would look like. > > -- > 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.'' > > _______________________________________________ > Haskell-Cafe mailing list > Haskell-Cafe@haskell.org > http://www.haskell.org/mailman/listinfo/haskell-cafe _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
