On Wed, Jul 15, 2020 at 02:40:39PM +0100, Dimitri John Ledkov wrote: > • No instance for (MonadFail Action) arising from a use of ‘fail’
AFAIK (slightly out of the loop), this is because fail is not a part of Monad any more https://downloads.haskell.org/~ghc/8.8.1/docs/html/users_guide/8.8.1-notes.html Upgrading shake will fix this, or it can be worked around in the meantime in pkg-haskell-tools by import Control.Monad.Fail as fail instance MonadFail Action where fail = Fail.fail Don't have time to upload it myself, but HTH. Cheers, -- Iain Lane [ i...@orangesquash.org.uk ] Debian Developer [ la...@debian.org ] Ubuntu Developer [ la...@ubuntu.com ]
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