pipes-3.0.0: Compositional pipelines

Control.Proxy.Prelude.Kleisli

Contents

Description

Utility functions for Kleisli arrows

Synopsis

# Core utility functions

foreverK :: Monad m => (a -> m a) -> a -> m bSource

Compose a '`K`'leisli arrow with itself forever

Use `foreverK` to abstract away the following common recursion pattern:

``` p a = do
...
a' <- respond b
p a'
```

Using `foreverK`, you can instead write:

``` p = foreverK \$ \a -> do
...
respond b
```

replicateK :: Monad m => Int -> (a -> m a) -> a -> m aSource

Repeat a '`K`'leisli arrow multiple times

liftK :: (Monad m, MonadTrans t) => (a -> m b) -> a -> t m bSource

Convenience function equivalent to `(lift .)`

``` liftK f >=> liftK g = liftK (f >=> g)

liftK return = return
```

hoistK :: (Monad m, MFunctor t) => (forall a. m a -> n a) -> (b' -> t m b) -> b' -> t n bSource

Convenience function equivalent to `(hoist f .)`

``` hoistK f p1 >-> hoistK f p2 = hoistK f (p1 >-> p2)

hoistK f idT = idT
```
``` hoistK f p1 >=> hoistK f p2 = hoistK f (p1 >=> p2)

hoistK f return = return
```
``` hoistK f . hoistK g = hoistK (f . g)

hoistK id = id
```

raiseK :: (Monad m, MFunctor t1, MonadTrans t2) => (q -> t1 m r) -> q -> t1 (t2 m) rSource

Convenience function equivalent to `(hoist lift .)`

``` raiseK p1 >-> raiseK p2 = raiseK (p1 >-> p2)

raiseK idT = idT
```
``` raiseK p1 >=> raiseK p2 = raiseK (p1 >=> p2)

raiseK return = return
```