Don't export `fst` (and alike) from `Prelude.Linear`
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- Haskell
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Description
It is surprising that Prelude.Linear exports the non-linear version of projection fst :: (a,b) -> a.
This tripped me up (with non-inspiring errors about multiplicity) when writing evalState:
- #404
I was naturally expecting that fst :: Consumable b => (a,b) -> a would be by default in scope if a fst is in scope. After all, we want linear programs when we import Prelude.Linear!
So, I suggest either to not export fst (and alike) or export them from Data.Tuple.Linear.
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
Inspect the exports in Prelude.Linear and the related API in Data.Tuple.Linear, then read the linked #404 context. Decide whether fst and related projections should be removed from Prelude.Linear or moved to Data.Tuple.Linear; done means the chosen export policy is consistent and documented by the resulting module interface.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- haskell
- Domain
- developer-experience
- Issue type
- Refactor
- Difficulty
- 5/5
- Estimated time
- Over a week
- Activity status
- Stale
- Clarity
- Mostly clear
- Newbie friendliness
- 35/100