Ticket #212 (new task)

Opened 8 months ago

Last modified 5 months ago

Investigate unexpected change with (Monad (Either e))

Reported by: SimonHengel Owned by:
Priority: major Milestone: 2.13.2
Version: 2.13.1 Keywords:
Cc:

Description

see: https://github.com/ghc/haddock/commit/47e6c8e77a4b8edbb1e4869ba5a0f76ee71ad8bb

Change History

Changed 8 months ago by SimonHengel

  • version set to 2.12.0
  • milestone set to 2.12.1

Changed 7 months ago by anonymous

  • milestone 2.12.1 deleted

Milestone 2.12.1 deleted

Changed 7 months ago by SimonHengel

  • version changed from 2.12.0 to 2.13.1
  • milestone set to 2.13.2

Changed 5 months ago by ross

  • type changed from task to defect
  • summary changed from Investigate unexpected change with (Monad (Either e)) instance to Instance contexts are not reduced, leaving them overly complex (and non-portable)

Haddock no longer reduces instance contexts, so the docs for Data.Ord display non-portable instances like 

(Eq [a], Ord a) => Ord [a]
(Eq (Maybe a), Ord a) => Ord (Maybe a)
Eq (Ptr a) => Ord (Ptr a)

which should be 

Ord a => Ord [a]
Ord a => Ord (Maybe a)
Ord (Ptr a)

This is presumably connected to GHC's lazy instance reduction.

Changed 5 months ago by SimonHengel

  • type changed from defect to task
  • summary changed from Instance contexts are not reduced, leaving them overly complex (and non-portable) to Investigate unexpected change with (Monad (Either e))

Ross, I think your issue has already been fixed by David: https://github.com/ghc/haddock/commit/6ccf78e15a525282fef61bc4f58a279aa9c21771

This is a different issue, I will revert the summary/type.

Please raise your voice if you think the issue is still eminent with ghc-7.6.2rc1.

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