6.2.9. New monadic failure desugaring mechanism¶
- MonadFailDesugaring¶
- Since:
8.0.1
Use the
MonadFail.failinstead of the legacyMonad.failfunction when desugaring refutable patterns indoblocks.
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.