[Scala 3] derived instances are not stack-safe
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Feature
- Dominant language
- Scala
- Stars
- 545
- Forks
- 66
- Avg merge
- 26m
- Merged PRs (30d)
- 2
Description
The following derivations are not stack-safe:
FunctorContravariant
This is because the shapeless 3 ErasedXXXInstances#map has mutual recursion between the Product and Coproduct instances when dealing with recursive sum types like List
Contributor guide
First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
Research direction
Start with shapeless 3's ErasedXXXInstances#map implementation, focusing on the mutual recursion between its Product and Coproduct instances. Check recursive sum-type derivations for Functor and Contravariant; done means those derivations no longer overflow the stack.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- scala
- Domain
- tooling
- Issue type
- Bug
- Difficulty
- 4/5
- Estimated time
- 3-5 days
- Activity status
- Stale
- Clarity
- Mostly clear
- Newbie friendliness
- 35/100