[Haskell-cafe] Control.Arrow being icky

Andrew Wagner wagner.andrew at gmail.com
Mon Feb 9 13:13:50 EST 2009


It's spelled 'Kleisli'. You spelled it 'Kliesli'

2009/2/9 Louis Wasserman <wasserman.louis at gmail.com>

> In GHCi, I import Control.Arrow, and Kliesli doesn't appear:
> Prelude Control.Arrow> :t Kliesli
>
> <interactive>:1:0: Not in scope: data constructor `Kliesli'
> Prelude Control.Arrow> :browse
> (<<^) :: (Arrow a) => a c d -> (b -> c) -> a b d
> (>>^) :: (Arrow a) => a b c -> (c -> d) -> a b d
> class (Control.Category.Category a) => Arrow a where
>   arr :: (b -> c) -> a b c
>   first :: a b c -> a (b, d) (c, d)
>   second :: a b c -> a (d, b) (d, c)
>   (***) :: a b c -> a b' c' -> a (b, b') (c, c')
>   (&&&) :: a b c -> a b c' -> a b (c, c')
> class (Arrow a) => ArrowApply a where app :: a (a b c, b) c
> class (Arrow a) => ArrowChoice a where
>   left :: a b c -> a (Either b d) (Either c d)
>   right :: a b c -> a (Either d b) (Either d c)
>   (+++) :: a b c -> a b' c' -> a (Either b b') (Either c c')
>   (|||) :: a b d -> a c d -> a (Either b c) d
> class (Arrow a) => ArrowLoop a where
>   loop :: a (b, d) (c, d) -> a b c
> newtype (ArrowApply a) => ArrowMonad a b = ArrowMonad (a () b)
> class (ArrowZero a) => ArrowPlus a where
>   (<+>) :: a b c -> a b c -> a b c
> class (Arrow a) => ArrowZero a where zeroArrow :: a b c
> newtype Kleisli m a b = Kleisli {runKleisli :: a -> m b}
> (^<<) :: (Arrow a) => (c -> d) -> a b c -> a b d
> (^>>) :: (Arrow a) => (b -> c) -> a c d -> a b d
> leftApp :: (ArrowApply a) => a b c -> a (Either b d) (Either c d)
> returnA :: (Arrow a) => a b b
> (<<<) ::
>   (Control.Category.Category cat) => cat b c -> cat a b -> cat a c
> (>>>) ::
>   (Control.Category.Category cat) => cat a b -> cat b c -> cat a c
>
> Does anybody know what's going on?
>
> Louis Wasserman
> wasserman.louis at gmail.com
>
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