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Within LTS Haskell 24.6 (ghc-9.10.2)
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backprop Prelude.Backprop.Num Alias for fmapConst.
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backprop Prelude.Backprop.Num Alias for fmap.
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<$ ) :: Functor f => a -> f b -> f acabal-install-solver Distribution.Solver.Compat.Prelude Replace all locations in the input with the same value. The default definition is fmap . const, but this may be overridden with a more efficient version.
Examples
Perform a computation with Maybe and replace the result with a constant value if it is Just:>>> 'a' <$ Just 2 Just 'a' >>> 'a' <$ Nothing Nothing
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<$> ) :: Functor f => (a -> b) -> f a -> f bcabal-install-solver Distribution.Solver.Compat.Prelude An infix synonym for fmap. The name of this operator is an allusion to $. Note the similarities between their types:
($) :: (a -> b) -> a -> b (<$>) :: Functor f => (a -> b) -> f a -> f b
Whereas $ is function application, <$> is function application lifted over a Functor.Examples
Convert from a Maybe Int to a Maybe String using show:>>> show <$> Nothing Nothing
>>> show <$> Just 3 Just "3"
Convert from an Either Int Int to an Either Int String using show:>>> show <$> Left 17 Left 17
>>> show <$> Right 17 Right "17"
Double each element of a list:>>> (*2) <$> [1,2,3] [2,4,6]
Apply even to the second element of a pair:>>> even <$> (2,2) (2,True)
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classy-prelude-conduit ClassyPrelude.Conduit A synonym for =$= for backwards compatibility. Since 0.4.0
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classy-prelude-conduit ClassyPrelude.Conduit The connect-and-resume operator. This does not close the Conduit, but instead returns it to be used again. This allows a Conduit to be used incrementally in a large program, without forcing the entire program to live in the Sink monad. Leftover data returned from the Sink will be discarded. Mnemonic: connect + do more. Since 1.0.17
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classy-prelude-conduit ClassyPrelude.Conduit Continue processing after usage of =$$+. Connect a SealedConduitT to a sink and return the output of the sink together with a new SealedConduitT. Since 1.0.17
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classy-prelude-conduit ClassyPrelude.Conduit Same as =$$++, but doesn't include the updated SealedConduitT. NOTE In previous versions, this would cause finalizers to run. Since version 1.3.0, there are no finalizers in conduit. Since 1.0.17
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classy-prelude-conduit ClassyPrelude.Conduit Deprecated fusion operator. Since 0.4.0
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<$?> ) :: Filtrable f => (a -> Maybe b) -> f a -> f bfiltrable Data.Filtrable Infix synonym of mapMaybe