Remove noncanonical definitions #206
Closed
Conversation
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This appeases the -Wnoncanonical-monoid-instances and -Wnoncanonical-monad-instances warnings. These warnings exist because a future GHC release may treat noncanonical definitions as errors. See also: https://gitlab.haskell.org/ghc/ghc/-/wikis/proposal/monad-of-no-return https://gitlab.haskell.org/ghc/ghc/-/wikis/proposal/semigroup-monoid
phadej
reviewed
Feb 23, 2025
|
|
||
| instance (Repeat f, Monoid a) => Monoid (Zippy f a) where | ||
| mempty = Zippy $ repeat mempty | ||
| mappend (Zippy x) (Zippy y) = Zippy $ zipWith mappend x y |
Collaborator
There was a problem hiding this comment.
this change is potentially changing behavior, so no, I won't do these. Until GHC starts to treat them as errors, I won't cleanup these warnings.
|
There seems to be some confusion elsewhere about the reasoning here. @phadej's argument seems to be (please correct me if I misunderstood it) that defining |
Collaborator
Yes. |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
3 participants
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
This appeases the -Wnoncanonical-monoid-instances and -Wnoncanonical-monad-instances warnings. These warnings exist because a future GHC release may treat noncanonical definitions as errors.
See also:
https://gitlab.haskell.org/ghc/ghc/-/wikis/proposal/monad-of-no-return
https://gitlab.haskell.org/ghc/ghc/-/wikis/proposal/semigroup-monoid