patch applied (haskell-prime-status): add ""Make $ left
associative, like application"
apfelmus at quantentunnel.de
Wed Apr 23 07:41:35 EDT 2008
Dan Doel wrote:
> 3) Left associative ($) is consistent with left associative ($!).
> (f $! x) y z
> ((f $! x) $! y) $! z
> Left associative, these are:
> f $! x $ y $ z
> f $! x $! y $! z
Nice! Subconsciously, the fact that ($!) is currently not left
associative has always bitten me.
In the light of Cale's plan to make (.) equivalent to fmap , there is
also the option to redefine ($) to mean fmap . This would eliminate
the need for a special <$> for applicative functors.
Note that setting (.) or ($) = fmap subsumes function application,
because we have
fmap :: (a -> b) -> a -> b
for the /identity functor/. In other words, the current ($) and (.) are
just special cases of the general fmap . Unfortunately, the identity
functor currently can't be overloaded, although I think it would be
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