Conversation
SubTyper was introduced back when we still had equirecursive types. Back then it implemented the coinductive subtype checking algorithm, but since then it has had dual roles: it has checked subtyping between pairs of types and heaptypes, and it also checks whether the definition of a subtype is valid. Since these are two very different roles, it does not make sense to bundle them in a single utility. Split up the code and move each part to its users.
kripken
approved these changes
Mar 12, 2026
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
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
2 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Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be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.
SubTyper was introduced back when we still had equirecursive types. Back then it implemented the coinductive subtype checking algorithm, but since then it has had dual roles: it has checked subtyping between pairs of types and heaptypes, and it also checks whether the definition of a subtype is valid. Since these are two very different roles, it does not make sense to bundle them in a single utility. Split up the code and move each part to its users.