[Haskell-cafe] Monoid wants a (++) equivalent

Ross Paterson ross at soi.city.ac.uk
Wed Jul 1 14:26:51 EDT 2009

On Wed, Jul 01, 2009 at 10:55:39AM -0700, Bryan O'Sullivan wrote:
> Okay, here's a tentative plan that will help to figure out the answer. I'll
> build a fiddled base package that rewires the Monoid class to have (++) be the
> binary operator, and mappend as a synonym for it. I'll import the Monoid (++)
> into the Prelude. I'll see how much breaks. If that much builds smoothly, I'll
> see how much of the rest of Hackage builds, both with and without this custom
> base package. I'll follow up here with the results, along with a suggestion of
> how acceptable I think the observed level of breakage is.

Generalizing (++) will break some Haskell 98 code, e.g.

  append = (++)

I think that's a show-stopper.

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