6.2.9. New monadic failure desugaring mechanism¶
-
MonadFailDesugaring
¶ Since: 8.0.1 Use the
MonadFail.fail
instead of the legacyMonad.fail
function when desugaring refutable patterns indo
blocks.
The -XMonadFailDesugaring
extension switches the desugaring of
do
-blocks to use MonadFail.fail
instead of Monad.fail
.
This extension is enabled by default since GHC 8.6.1, under the MonadFail Proposal (MFP).
This extension is temporary, and will be deprecated in a future release.