Proposal #3339: Add (+>) as a synonym for mappend

Ian Lynagh igloo at earth.li
Mon Nov 7 16:44:38 CET 2011


On Sun, Nov 06, 2011 at 11:58:10PM -0500, Edward Kmett wrote:
> On Sun, Nov 6, 2011 at 8:33 PM, Ian Lynagh <igloo at earth.li> wrote:
> 
> > On Mon, Nov 07, 2011 at 01:13:23AM +0000, Duncan Coutts wrote:
> > >
> > > So maybe we should just conclude that pretty printing should be left
> > > associative, building from the left.
> >
> > To clarify, Duncan and I are now thinking that as pretty builds
> > left-to-right strings, perhaps it is natural that the operators in
> >
> >    a <+> b <> c <+> d <> e <+> ...
> >
> > should be left-infix, as it is natural to read this as "a then b, then
> > c, ..."
> >
> 
> I'm not sure I follow.
> 
> It would seem that accessing a then (b then ...) would require me to have
> it associated to the right, otherwise I have
> 
> (((((...(a then b) then c) and I can't even start figuring out what I'm
> going to do until I crawl my way down to the bottom.

You're talking about the relative performance of the two options. I'm
talking about the semantics you would expect if you didn't think about
performance.


Thanks
Ian




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