Safe Haskell	Safe-Inferred
Language	Haskell2010

Effectful.Writer.Dynamic

Contents

Effect
- Handlers
  - Local
  - Shared
Operations

Description

The dynamically dispatched variant of the Writer effect.

Note: unless you plan to change interpretations at runtime, it's recommended to use one of the statically dispatched variants, i.e. Effectful.Writer.Static.Local or Effectful.Writer.Static.Shared.

Synopsis

data Writer w :: Effect where
- Tell :: w -> Writer w m ()
- Listen :: m a -> Writer w m (a, w)
runWriterLocal :: Monoid w => Eff (Writer w : es) a -> Eff es (a, w)
execWriterLocal :: Monoid w => Eff (Writer w : es) a -> Eff es w
runWriterShared :: Monoid w => Eff (Writer w : es) a -> Eff es (a, w)
execWriterShared :: Monoid w => Eff (Writer w : es) a -> Eff es w
tell :: (HasCallStack, Writer w :> es) => w -> Eff es ()
listen :: (HasCallStack, Writer w :> es) => Eff es a -> Eff es (a, w)
listens :: (HasCallStack, Writer w :> es) => (w -> b) -> Eff es a -> Eff es (a, b)

Effect

data Writer w :: Effect where Source #

Provide access to a write only value of type w.

Constructors

Tell :: w -> Writer w m ()
Listen :: m a -> Writer w m (a, w)

Instances

Instances details

type DispatchOf (Writer w) Source #
Instance details Defined in Effectful.Writer.Dynamic type DispatchOf (Writer w) = 'Dynamic

Handlers

Local

runWriterLocal :: Monoid w => Eff (Writer w : es) a -> Eff es (a, w) Source #

Run the Writer effect and return the final value along with the final output (via Effectful.Writer.Static.Local).

execWriterLocal :: Monoid w => Eff (Writer w : es) a -> Eff es w Source #

Run a Writer effect and return the final output, discarding the final value (via Effectful.Writer.Static.Local).

Shared

runWriterShared :: Monoid w => Eff (Writer w : es) a -> Eff es (a, w) Source #

Run the Writer effect and return the final value along with the final output (via Effectful.Writer.Static.Shared).

execWriterShared :: Monoid w => Eff (Writer w : es) a -> Eff es w Source #

Run the Writer effect and return the final output, discarding the final value (via Effectful.Writer.Static.Shared).

Operations

tell :: (HasCallStack, Writer w :> es) => w -> Eff es () Source #

Append the given output to the overall output of the Writer.

listen :: (HasCallStack, Writer w :> es) => Eff es a -> Eff es (a, w) Source #

Execute an action and append its output to the overall output of the Writer.

listens :: (HasCallStack, Writer w :> es) => (w -> b) -> Eff es a -> Eff es (a, b) Source #

Execute an action and append its output to the overall output of the Writer, then return the final value along with a function of the recorded output.

listens f m ≡ second f <$> listen m