#3335: make some Applicative functions into methods, and split off Data.Functor
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Reporter: ross | Owner:
Type: proposal | Status: new
Priority: normal | Component: libraries/base
Version: | Severity: normal
Keywords: | Testcase:
Os: Unknown/Multiple | Architecture: Unknown/Multiple
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The following functions
{{{
(<$) :: Functor f => a -> f b -> f a
(*>) :: Applicative f => f a -> f b -> f b
(<*) :: Applicative f => f a -> f b -> f a
some :: Alternative f => f a -> f [a]
many :: Alternative f => f a -> f [a]
}}}
are moved into the corresponding classes, with the existing
implementations as default definitions. This gives people creating
instances the option of defining specialized implementations of these
functions, though they should be equivalent to the default definitions.
Although (<$) is now a method of the Functor class, it is hidden in the
re-export by the Prelude, Control.Monad and Monad. The new module
Data.Functor exposes the full class, plus the function (<$>). These are
also re-exported by Control.Applicative.
Discussion on [email protected] to 20th July 2009.
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/3335>
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