Use newtype instead of data says that the change decreases laziness in the presence of -XStrictData
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Description
Using newtype over data shouldn't make a difference to the strictness when -XStrictData is active.
src/Foo.hs:73:1: Suggestion: Use newtype instead of data
Found:
data Bus = Bus{unBus :: Signed 16}
Why not:
newtype Bus = Bus{unBus :: Signed 16}
Note: decreases laziness
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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 by reproducing the src/Foo.hs example with -XStrictData and inspect the HLint rule that emits “Use newtype instead of data.” Verify how the suggestion and its “decreases laziness” note are derived. Done means the tool no longer reports an incorrect strictness difference for this case, with regression coverage for the example.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- haskell
- Domain
- tooling
- Issue type
- Bug
- Difficulty
- 4/5
- Estimated time
- 3-5 days
- Activity status
- Stale
- Clarity
- Mostly clear
- Newbie friendliness
- 35/100