Refactor function returning an `IO (Either String _)` to use MonadError instead #57

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opened 2020-07-07 23:48:46 +02:00 by schmittlauch · 0 comments

schmittlauch commented

2020-07-07 23:48:46 +02:00

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Most functions doing network lookups return an IO (Either String ActuallyWantedType) to indicate the possibility and cause of an error.

For better composability, these could be refactored to use MonadError String, MonadIO instead. Then several of these actions can be composed, fail using throwError and then expose this error only through catchError or runExceptT.

Most functions doing network lookups return an `IO (Either String ActuallyWantedType)` to indicate the possibility and cause of an error. For better composability, these could be refactored to use `MonadError String, MonadIO` instead. Then several of these actions can be composed, fail using `throwError` and then expose this error only through `catchError` or `runExceptT`.