On Mon, 2009-01-19 at 22:12 -0500, S. Doaitse Swierstra wrote: > On 17 jan 2009, at 22:22, Derek Elkins wrote: > > > On Thu, 2009-01-15 at 13:40 +0100, Apfelmus, Heinrich wrote: > >> Eugene Kirpichov wrote: > >>> Well, your program is not equivalent to the C++ version, since it > >>> doesn't bail on incorrect input. > >> > >> Oops. That's because my assertion > >> > >> show . read = id > >> > >> is wrong. We only have > >> > >> read . show = id > >> show . read <= id (in the "less defined than" sense) > > > > No, you only have > > read . show = id which often doesn't hold in practice. > > show . read </= id > > You do not even have that; the read may remove surplus parentheses > which will not be reinserted by the show. > > Doaitse >
My notation is show . read is not less than or equal to id. That covers that case. The particular example I was thinking of was actually simply whitespace. _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe