Polysemy.Resume.Resume

Documentation

resume :: forall err eff r a. Member (Resumable err eff) r => Sem (eff ': r) a -> (err -> Sem r a) -> Sem r a

Execute the action of a regular effect eff so that any error of type err that maybe be thrown by the (unknown) interpreter used for eff will be caught here and handled by the handler argument. This is similar to catch with the additional guarantee that the error will have to be explicitly matched, therefore preventing accidental failure to handle an error and bubbling it up to main. It also imposes a membership of Resumable err eff on the program, requiring the interpreter for eff to be adapted with resumable.

data Resumer :: Effect where
  MainProgram :: Resumer m Int

makeSem ''Resumer

interpretResumer ::
  Member (Resumable Boom Stopper) r =>
  InterpreterFor Resumer r
interpretResumer =
  interpret \ MainProgram ->
    resume (192 <$ stopBang) \ _ ->
      pure 237

resumeRe :: forall err eff r a. Sem (eff ': r) a -> (err -> Sem (Resumable err eff ': r) a) -> Sem (Resumable err eff ': r) a

resuming :: forall err eff r a. Member (Resumable err eff) r => (err -> Sem r a) -> Sem (eff ': r) a -> Sem r a

Flipped variant of resume.

resumingRe :: forall err eff r a. (err -> Sem (Resumable err eff ': r) a) -> Sem (eff ': r) a -> Sem (Resumable err eff ': r) a

Flipped variant of resumeRe.

resumeAs :: forall err eff r a. Member (Resumable err eff) r => a -> Sem (eff ': r) a -> Sem r a

Variant of resume that unconditionally recovers with a constant value.

resume_ :: forall err eff r. Member (Resumable err eff) r => Sem (eff ': r) () -> Sem r ()

Convenience specialization of resume that silently discards errors for void programs.

resumeHoist :: forall err eff err' r a. Members [Resumable err eff, Stop err'] r => (err -> err') -> Sem (eff ': r) a -> Sem r a

Variant of resume that propagates the error to another Stop effect after applying a function.

resumeHoistAs :: forall err eff err' r. Members [Resumable err eff, Stop err'] r => err' -> InterpreterFor eff r

Variant of resumeHoist that uses a constant value.

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

Variant of resumeHoist that uses the unchanged error.

resumeEither :: forall err eff r a. Member (Resumable err eff) r => Sem (eff ': r) a -> Sem r (Either err a)

Variant of restop that immediately produces an Either.

resumeHoistError :: forall err eff err' r a. Members [Resumable err eff, Error err'] r => (err -> err') -> Sem (eff ': r) a -> Sem r a

Variant of resume that propagates the error to an Error effect after applying a function.

resumeHoistErrorAs :: forall err eff err' r a. Members [Resumable err eff, Error err'] r => err' -> Sem (eff ': r) a -> Sem r a

Variant of resumeHoistError that uses the unchanged error.

resumeError :: forall err eff r a. Members [Resumable err eff, Error err] r => Sem (eff ': r) a -> Sem r a

Variant of resumeHoistError that uses the unchanged error.