MonadTransControl
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object MonadTransControl
| package control
A function that runs a transformed monad T n on the monadic state that
was captured by liftWith
A function that runs a transformed monad T n on the monadic state that
was captured by liftWith
A Run function yields a computation in M that returns the monadic state
of T. This state can later be used to restore a T computation using
restoreT.
Monadic state of T.
liftWith is similar to liftM in that it lifts a computation from the
argument monad to the constructed monad.
liftWith is similar to liftM in that it lifts a computation from the
argument monad to the constructed monad.
Instances should satisfy similar laws as the MonadTrans laws:
liftWith . const . return = return liftWith (const (m >>= f)) = liftWith (const m) >>= liftWith . const . f
The difference with liftM is that before lifting the M computation
liftWith captures the state of T. It then provides the M computation
with a Run function that allows running T[M, ?] computations in M
(for all M) on the captured state.
Construct a T computation from the monadic state of T that is returned
from a Run function.
Construct a T computation from the monadic state of T that is returned
from a Run function.
Instances should satisfy:
liftWith (\run -> run t) >>= restoreT . return = t
An often used composition: control f = liftWith f >>= restoreT . return