different flavours of Monad Template Library
g9ks157k at acme.softbase.org
Mon Jan 12 10:26:16 EST 2009
Am Samstag, 10. Januar 2009 22:30 schrieb Ross Paterson:
> On Sat, Jan 10, 2009 at 10:20:59PM +0100, Henning Thielemann wrote:
> > What are the changes from transformers-0.0.1.0 to transformers-0.1.0.0 ?
> Instances for Applicative and Alternative.
And we should try to make Applicative a superclass of Monad and drop MonadPlus
in favor of Alternative + Monad. It would be probably even better to have
somethink like Alternative/MonadPlus for functors (since functors are the
most general concept at this point) and drop Alternative and MonadPlus (or
use the name „Alternative“ for this new class). It’s terrible to explain all
this legacy (Applicative not being superclass of Monad, two different classes
for monoid functors) to students and to mention Applicative in a class
context which already mentions Monad.
However, we’ll probably need something like John Meachem’s class alias
proposal to make such a transition as smooth as possible. Anyone who wants
to hack GHC in this regard?
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