Control.Monad.Levels.RWS

Note that the original definitions are used for the various reader, writer and state computations: as such, if there is (for example) another level that satisfies 'IsReader r' above the one that satisfies 'IsRWS r w s' in the stack, then calling ask will use the higher level.

Documentation

type HasRWS r w s m = SatisfyConstraint (IsRWS r w s) m

class (IsReader r m, IsWriter w m, IsState s m) => IsRWS r w s m

Defined as another class rather than an alias in case you need to ensure the same level satisfies all three constraints (and to have a specific ValidConstraint instance).

Instances

(MonadTower m, Monoid w) => IsRWS r w s (RWST r w s m)

(MonadTower m, Monoid w) => IsRWS r w s (RWST r w s m)

Monoid w => ValidConstraint (IsRWS r w s)

type ConstraintSatisfied (IsRWS r w s) m

module Control.Monad.Levels.Reader

module Control.Monad.Levels.Writer

module Control.Monad.Levels.State