Close over kind variables when computing fixed type variables #973
Conversation
This file contains 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
To make the 9.0.1 build work, I've temporarily: * Relaxed the upper version bounds on `base` for the `cassava` and `vector-binary-instances` packages, and * Made the `hlint` job use GHC 8.10.4, not 9.0.1.
Previously, `buildStab` would not consider kind variables when determining which type variables need to be fixed in a generated `Lens`'s type signature. This was not a problem in older versions of `lens`, which aggressively dropped kind variables, but now that `lens` attempts to include kind variables in generated type signatures, this problem has risen to the surface, resulting in the problems observed in #972. The solution is to take the set of fixed type variables in `buildStab` and close over kind variables. For more information, refer to the comments I have left near `closeOverKinds`. Fixes #972.
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
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Outdated suggestions cannot be applied.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.
Previously,
buildStabwould not consider kind variables when determining which type variables need to be fixed in a generatedLens's type signature. This was not a problem in older versions oflens, which aggressively dropped kind variables, but now thatlensattempts to include kind variables in generated type signatures, this problem has risen to the surface, resulting in the problems observed in #972.The solution is to take the set of fixed type variables in
buildStaband close over kind variables. For more information, refer to the comments I have left nearcloseOverKinds.Fixes #972.