Twan van Laarhoven wrote:
I some cases Applicative is a huge win. Simon's argument is that it is not
possible to use consistently everywhere. I agree that we should strive
to have a
single style for different cases in a single function. However, there
are a lot
of functions that become significantly simpler with Applicative. Random
example:
dsLookupGlobalId :: Name -> DsM Id
dsLookupGlobalId name
= tyThingId <$> dsLookupGlobal name
Not only is it shorter than the corresponding monadic code, it is also
conceptually simpler.
and it also has nothing to do with Applicative, only Functor; it could
be fmap
dsLookupGlobalId :: Name -> DsM Id
dsLookupGlobalId name
= tyThingId `fmap` dsLookupGlobal name
or
= fmap tyThingId (dsLookupGlobal name)
I suppose some of your examples are more difficult than this one,
though. Please don't forget Control.Monad.liftM# and Control.Monad.ap
(though it's debatable if it's preferable to use those than the
Applicative names liftA# and especially <*>, or if even the
monad-versions make the code too confusing)
~Isaac
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