monadlib
monadlib copied to clipboard
Build failure with GHC 9.2.1
src/MonadLib.hs:200:10: error:
• Non type-variable argument in the constraint: RunM m (a, i) r
(Use FlexibleContexts to permit this)
• In the instance declaration for ‘RunM (WriterT i m) a r’
|
200 | instance (Monoid i, RunM m (a,i) r) => RunM (WriterT i m) a r where
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
src/MonadLib.hs:203:10: error:
• Non type-variable argument in the constraint: RunM m (a, i) r
(Use FlexibleContexts to permit this)
• In the instance declaration for ‘RunM (StateT i m) a (i -> r)’
|
203 | instance RunM m (a,i) r => RunM (StateT i m) a (i -> r) where
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
src/MonadLib.hs:206:10: error:
• Non type-variable argument
in the constraint: RunM m (Either i a) r
(Use FlexibleContexts to permit this)
• In the instance declaration for ‘RunM (ExceptionT i m) a r’
|
206 | instance RunM m (Either i a) r => RunM (ExceptionT i m) a r where
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
src/MonadLib.hs:212:10: error:
• Non type-variable argument
in the constraint: RunM m (Maybe (a, ChoiceT m a)) r
(Use FlexibleContexts to permit this)
• In the instance declaration for ‘RunM (ChoiceT m) a r’
|
212 | instance RunM m (Maybe (a,ChoiceT m a)) r => RunM (ChoiceT m) a r where
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
cabal: Failed to build monadLib-3.10.
This might be related to this change?! https://gitlab.haskell.org/ghc/ghc/-/wikis/migration/9.2#undecidableinstances-no-longer-implies-flexiblecontexts-in-instance-declarations
As a Hackage trustee, I have created a Hackage revision that should prevent users from running into this error: https://hackage.haskell.org/package/monadLib-3.10/revisions/