[Haskell-cafe] Either as a Monad instance

[Brian Hulley]

Ross Paterson wrote:
> On Tue, Oct 03, 2006 at 07:52:54AM -0400, Lennart Augustsson wrote:
>> Yes, having fail in the Monad is a horrible wart.
>
> (As far as I know, it's there for the translation of pattern match
> failure in do-expressions.)

I think it would be much less of a wart if the signature for fail was just:

    fail :: m a

because what's the point of the String argument anyway (other than trying to 
hack a kind of half-baked debug facility into the language)?

Regards, Brian.
-- 
Logic empowers us and Love gives us purpose.
Yet still phantoms restless for eras long past,
congealed in the present in unthought forms,
strive mightily unseen to destroy us.

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