{- | 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 m h = send (Catch m h pure)