OneOf?
Nobody has claimed this yet.
Assessment
- Difficulty
- 2/5
- Estimated time
- 1-3 hours
- Newbie friendliness
- 35/100
- Issue type
- Feature
- Clarity
- Mostly clear
- Activity status
- Stale
- Domain
- backend
Research direction
Start by reading the existing parser alternatives and error-combination operators in the library to see whether they already provide lazy, as-needed parsing. The issue includes a proposed oneOf implementation but names no files or tests; identify the relevant entry points and tests before deciding whether a new helper is needed. Done means establishing whether the helper exists or, if it does not, adding and testing the proposed behavior.
Written by the indexing model from the issue text.
Description
Feels like we probably already have a oneOf function that can make sure that not all branches are evaluated at once (to ensure efficient as-needed parsing), since using alt naively can lead to really really slow decoding, but I honestly don't know where it is. Is there something I'm missing that already implements this?:
oneOf :: forall f a
. Foldable f
=> f (Foreign -> F a)
-> Foreign
-> F a
oneOf f js = go (fromFoldable f) js
where
go (read : xs) js = do
case runExcept (read js) of
Right pv -> pure pv
Left e -> do
case runExcept (go xs js) of
Right pv' -> pure pv'
Left e' -> throwError (e <> e')
go Nil _ = do
throwError $ pure (ForeignError "No more parsers to attempt in oneOf")
If not, I could PR this, but feels like it probably exists as a simple combination of some operators.
- Dominant language
- PureScript
- Stars
- 64
- Forks
- 42
- Avg merge
- 2d 6h
- Merged PRs (30d)
- 1
Getting set up
- No Dockerfile or Docker Compose file
- Has a pull request template
- No contributing 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.
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