Polysemy.Resume.Resumable

Documentation

distribEither :: Functor f => f () -> (f (Either err a) -> res) -> Either err (f a) -> res

resumable :: forall (eff :: Effect) (err :: *) (r :: EffectRow). InterpreterFor eff (Stop err ': r) -> InterpreterFor (Resumable err eff) r

Convert a bare interpreter for eff, which (potentially) uses Stop to signal errors, into an interpreter for Resumable.

>>> run $ resumable interpretStopper (interpretResumer mainProgram)
237

resumableError :: forall eff err r. InterpreterFor eff (Error err ': (Stop err ': r)) -> InterpreterFor (Resumable err eff) r

Convert an interpreter for eff that uses Error into one using Stop and wrap it using resumable.

resumableOr :: forall eff err unhandled handled r. Member (Error unhandled) r => (err -> Either unhandled handled) -> InterpreterFor eff (Stop err ': r) -> InterpreterFor (Resumable handled eff) r

Convert an interpreter for eff that throws errors of type err into a Resumable, but limiting the errors handled by consumers to the type handled, which rethrowing Errors of type unhandled.

The function canHandle determines how the errors are split.

newtype Blip =
  Blip { unBlip :: Int }
  deriving (Eq, Show)

bangOnly :: Boom -> Either Text Blip
bangOnly = \case
  Bang n -> Right (Blip n)
  Boom msg -> Left msg

interpretResumerPartial ::
  Member (Resumable Blip Stopper) r =>
  InterpreterFor Resumer r
interpretResumerPartial =
  interpret \ MainProgram ->
    resume (192 <$ stopBang) \ (Blip num) ->
      pure (num * 3)

>>> runError (resumableFor bangOnly interpretStopper (interpretResumerPartial mainProgram))
Right 39

resumableFor :: forall eff err handled r. Member (Error err) r => (err -> Maybe handled) -> InterpreterFor eff (Stop err ': r) -> InterpreterFor (Resumable handled eff) r

Variant of resumableOr that uses Maybe and rethrows the original error.

catchResumable :: forall eff handled err r. Members [eff, Error err] r => (err -> Maybe handled) -> InterpreterFor (Resumable handled eff) r

Reinterpreting variant of resumableFor.

runAsResumable :: forall err eff r. Members [Resumable err eff, Stop err] r => InterpreterFor eff r

Interpret an effect eff by wrapping it in Resumable and Stop and leaving the rest up to the user.