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

David Roundy droundy at darcs.net
Thu Jun 21 09:41:17 EDT 2007

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

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