[Haskell-cafe] Re: [darcs-devel] advice on GADT type witnesses needed

[David Roundy]

On Thu, Jun 21, 2007 at 10:51:25AM +0100, Simon Peyton-Jones wrote:
> Good idea.  I'll improve the message by adding the suggestion to use a
> case expression instead.

Or do notation.  I almost always prefer do notation, even if it means
something like:

  fromJust $ do a' :< b' <- commute (b :< a)
                a'' :< c' <- commute (c :< a')
                return a'
-- 
David Roundy
http://www.darcs.net