ndmitchell / ndmitchell/hoogle
Hoogle can't find bisequence unless type constraints are specified
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Description
I searched for t (f a) (f b) -> f (t a b) and got:
No results found
If I add type constraints then everything works fine.
For (Bitraversable t, Applicative f) => t (f a) (f b) -> f (t a b) result is:
bisequenceA :: (Bitraversable t, Applicative f) => t (f a) (f b) -> f (t a b)
bisequence :: (Bitraversable t, Applicative f) => t (f a) (f b) -> f (t a b)
However such search request (without type constraints!) t a b -> (a -> f c) -> (b -> f d) -> f (t c d) gives expected result:
bifor :: (Bitraversable t, Applicative f) => t a b -> (a -> f c) -> (b -> f d) -> f (t c d)
biforM :: (Bitraversable t, Applicative f) => t a b -> (a -> f c) -> (b -> f d) -> f (t c d)
It seems that everything breaks here -- t (f a) (f b)
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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 constrained and unconstrained searches in Hoogle and compare their results. Trace how queries containing t (f a) (f b) are parsed and matched against bisequence and bisequenceA. Done means the unconstrained query returns the expected functions without regressing the existing bifor search.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- haskell
- Domain
- search
- Issue type
- Bug
- Difficulty
- 4/5
- Estimated time
- 3-5 days
- Activity status
- Stale
- Clarity
- Mostly clear
- Newbie friendliness
- 35/100