Tactics support for using given constraints #534
Merged
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
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Outdated suggestions cannot be applied.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.
This PR allows tactics to use methods from given constraints, meaning it can solve holes like this:
It will not, however, discover instances. So this one won't solve:
There's quite a lot of finicky details going on in order to support this. The primary challenge is that our types are running after the typechecker has finished, meaning it's already solved the constraints and inlined their evidence. Our solution is to look up the written polymorphic type and unify it with the final, typechecked type. We can use the polymorphic type to find the theta context, and instantiate every class method in the theta.
In addition, this PR fixes a subtle bug in our unification code, which could cause skolems to unify in some circumstances.
Furthermore, it adds a tie-breaker to the scoring metric to prefer shorter programs.