{- | An effect modelling catchable failure when used with 'Control.Effect.Throw.Throw'.

Predefined carriers:

* "Control.Carrier.Error.Either" (with 'Control.Effect.Throw.Throw')

@since 1.0.0.0
-}
module Control.Effect.Catch
( -- * Catch effect
  Catch(..)
, catchError
  -- * Re-exports
, Algebra
, Has
, run
) where

import Control.Algebra
import Control.Effect.Catch.Internal (Catch(..))

-- | Run a computation which can throw errors with a handler to run on error.
--
-- Errors thrown by the handler will escape up to the nearest enclosing 'catchError' (if any). Note that this effect does /not/ handle errors thrown from impure contexts such as IO, nor will it handle exceptions thrown from pure code. If you need to handle IO-based errors, consider if @fused-effects-exceptions@ fits your use case; if not, use 'Control.Monad.IO.Class.liftIO' with 'Control.Exception.try' or use 'Control.Exception.catch' from outside the effect invocation.
--
-- @
-- runError ('Control.Effect.Throw.throwError' e `catchError` f) = runError (f e)
-- @
--
-- @since 0.1.0.0
catchError :: Has (Catch e) sig m => m a -> (e -> m a) -> m a
catchError :: forall e (sig :: (* -> *) -> * -> *) (m :: * -> *) a.
Has (Catch e) sig m =>
m a -> (e -> m a) -> m a
catchError m a
m e -> m a
h = forall (eff :: (* -> *) -> * -> *) (sig :: (* -> *) -> * -> *)
       (m :: * -> *) a.
(Member eff sig, Algebra sig m) =>
eff m a -> m a
send (forall (m :: * -> *) a e. m a -> (e -> m a) -> Catch e m a
Catch m a
m e -> m a
h)
{-# INLINE catchError #-}