| Safe Haskell | None |
|---|---|
| Language | Haskell2010 |
Bluefin.Reader
Synopsis
- data Reader r (e :: Effects)
- runReader :: forall r (es :: Effects) a. r -> (forall (e :: Effects). Reader r e -> Eff (e :& es) a) -> Eff es a
- ask :: forall (e :: Effects) (es :: Effects) r. e :> es => Reader r e -> Eff es r
- asks :: forall (e :: Effects) (es :: Effects) r a. e :> es => Reader r e -> (r -> a) -> Eff es a
- local :: forall (e1 :: Effects) (es :: Effects) r a. e1 :> es => Reader r e1 -> (r -> r) -> Eff es a -> Eff es a
Documentation
Reader is Bluefin's version of the
Control.Monad.Trans.Reader monad. local allows you to
locally override the value in the Reader handle in a
well-scoped way. The original value will be restored when you
exit the local block regardless of whether the exit was
normal or via an exception .
Handle
data Reader r (e :: Effects) #
Instances
| e :> es => OneWayCoercible (Reader r e :: Type) (Reader r es :: Type) | |
Defined in Bluefin.Internal Methods oneWayCoercibleImpl :: OneWayCoercibleD (Reader r e) (Reader r es) # | |
| Handle (Reader r) | |
| CloneableHandle (Reader r) | |
Defined in Bluefin.Internal.CloneableHandle Methods | |
Handlers
Effectful operations
Read the value. Note that ask has the property that these two
operations are always equivalent:
do r1 <- ask re r2 <- ask re pure (r1, r2)
do r <- ask re pure (r, r)