[GHC] #8813: further support deriving instances Typeable1, Typeable2, etc
#8813: further support deriving instances Typeable1, Typeable2, etc ----------------------------+---------------------------------------------- Reporter: maeder | Owner: Type: task | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.8.1-rc1 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: GHC rejects valid program Unknown/Multiple | Test Case: Difficulty: Unknown | Blocking: Blocked By: | Related Tickets: | ----------------------------+---------------------------------------------- ghc-7.8.20140130 complains with {{{ Not in scope: type constructor or class ‛Typeable2’ Perhaps you meant ‛Typeable’ (imported from Data.Typeable) }}} changing Typeable2 to Typeable fixes it but is incompatible with ghc-7.6: {{{ Expecting two more arguments to `Gr' In the stand-alone deriving instance for `Typeable Gr' }}} -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/8813 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler
#8813: further support deriving instances Typeable1, Typeable2, etc ----------------------------------------------+---------------------------- Reporter: maeder | Owner: Type: task | Status: closed Priority: normal | Milestone: Component: Compiler | Version: Resolution: wontfix | 7.8.1-rc1 Operating System: Unknown/Multiple | Keywords: Type of failure: GHC rejects valid program | Architecture: Test Case: | Unknown/Multiple Blocking: | Difficulty: Unknown | Blocked By: | Related Tickets: ----------------------------------------------+---------------------------- Changes (by dreixel): * status: new => closed * resolution: => wontfix Comment: `Typeable2` no longer exists. If you need your code to work with both 7.8 and 7.6, you can use `CPP`. There's also `Data.OldTypeable` in 7.8. Some more information: https://ghc.haskell.org/trac/ghc/wiki/GhcKinds/PolyTypeable -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/8813#comment:1 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler
#8813: further support deriving instances Typeable1, Typeable2, etc ----------------------------------------------+---------------------------- Reporter: maeder | Owner: Type: task | Status: closed Priority: normal | Milestone: Component: Compiler | Version: Resolution: wontfix | 7.8.1-rc1 Operating System: Unknown/Multiple | Keywords: Type of failure: GHC rejects valid program | Architecture: Test Case: | Unknown/Multiple Blocking: | Difficulty: Unknown | Blocked By: | Related Tickets: ----------------------------------------------+---------------------------- Comment (by maeder): An (derived) instance of Data.!OldTypeable.Typeable cannot be used for a context based on Data.Typeable. Therefore Data.!OldTypeable is pretty useless. Is it no option (i.e. better) to make Typeable{1,..,7} behave like Typeable (with a warning)? -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/8813#comment:2 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler
#8813: further support deriving instances Typeable1, Typeable2, etc ----------------------------------------------+---------------------------- Reporter: maeder | Owner: Type: task | Status: closed Priority: normal | Milestone: Component: Compiler | Version: Resolution: wontfix | 7.8.1-rc1 Operating System: Unknown/Multiple | Keywords: Type of failure: GHC rejects valid program | Architecture: Test Case: | Unknown/Multiple Blocking: | Difficulty: Unknown | Blocked By: | Related Tickets: ----------------------------------------------+---------------------------- Comment (by carter): @maeder, nope, please use CPP. CPP allows us to better support evolving / improving GHC while still ensuring that code can work across multiple GHC versions. Please use it. :) -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/8813#comment:3 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler
#8813: further support deriving instances Typeable1, Typeable2, etc ----------------------------------------------+---------------------------- Reporter: maeder | Owner: Type: task | Status: closed Priority: normal | Milestone: Component: Compiler | Version: Resolution: wontfix | 7.8.1-rc1 Operating System: Unknown/Multiple | Keywords: Type of failure: GHC rejects valid program | Architecture: Test Case: | Unknown/Multiple Blocking: | Difficulty: Unknown | Blocked By: | Related Tickets: ----------------------------------------------+---------------------------- Comment (by maeder): What is the problem to add (renamed) copies of Typeable (named TypeableN) and add generic instances "TypeableN k => Typeable k" and re-export those via Data.Typeable? This would allow to test unmodified existing code!!! (These intermediate TypeableN classes may be marked to be deprecated later) -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/8813#comment:4 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler
#8813: further support deriving instances Typeable1, Typeable2, etc ----------------------------------------------+---------------------------- Reporter: maeder | Owner: Type: task | Status: closed Priority: normal | Milestone: Component: Compiler | Version: Resolution: wontfix | 7.8.1-rc1 Operating System: Unknown/Multiple | Keywords: Type of failure: GHC rejects valid program | Architecture: Test Case: | Unknown/Multiple Blocking: | Difficulty: Unknown | Blocked By: | Related Tickets: ----------------------------------------------+---------------------------- Comment (by simonpj): The biggest single problem is that RC1 has been out some weeks; RC2 is due today; full release next week. Moreover the person (Pedro) who was working on this area is probably heads-down on his ICFP submission (deadline 1 March). There was quite a bit of email traffic on this at the time all this was nailed down (months ago) and no objections. I'm honestly not sure of details of your proposal. Do you want to modify libraries only, or the compiler as well? Would you like to make a patch? Simon -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/8813#comment:5 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler
#8813: further support deriving instances Typeable1, Typeable2, etc ----------------------------------------------+---------------------------- Reporter: maeder | Owner: Type: task | Status: closed Priority: normal | Milestone: Component: Compiler | Version: Resolution: wontfix | 7.8.1-rc1 Operating System: Unknown/Multiple | Keywords: Type of failure: GHC rejects valid program | Architecture: Test Case: | Unknown/Multiple Blocking: | Difficulty: Unknown | Blocked By: | Related Tickets: ----------------------------------------------+---------------------------- Comment (by dreixel): Replying to [comment:4 maeder]:
What is the problem to add (renamed) copies of Typeable (named TypeableN) and add generic instances "TypeableN k => Typeable k" and re- export those via Data.Typeable? This would allow to test unmodified existing code!!!
(These intermediate TypeableN classes may be marked to be deprecated later)
I thought about ways to do this before, and never came to a reasonable solution. If you can find one, please let us know. For example, instances like `Typeable1 t => Typeable t` are impossible, as all `t`s match this instance head. I also didn't see how to reconcile the type of the old `typeOF` with the new poly-kinded `typeRep`. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/8813#comment:6 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler
#8813: further support deriving instances Typeable1, Typeable2, etc ----------------------------------------------+---------------------------- Reporter: maeder | Owner: Type: task | Status: closed Priority: normal | Milestone: Component: Compiler | Version: Resolution: wontfix | 7.8.1-rc1 Operating System: Unknown/Multiple | Keywords: Type of failure: GHC rejects valid program | Architecture: Test Case: | Unknown/Multiple Blocking: | Difficulty: Unknown | Blocked By: | Related Tickets: ----------------------------------------------+---------------------------- Comment (by maeder): The other simple alternative is to patch the renamer and rename the class Data.Typeable.TypeableN to Data.Typeable.Typeable. This surely does not reconcile typeOF and typeRep, but hand-written instances have been (sort of) deprecated long before. I'm not familiar with the internals of Data.Typeable but the following is not impossible: {{{ {-# Language FlexibleInstances, UndecidableInstances #-} class Pretty a where pretty :: a -> String instance Show a => Pretty a where pretty = show }}} Furthermore, Data.!OldTypeable should be removed. It's more harmful to provide a second incompatible Typeable class. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/8813#comment:7 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler
#8813: further support deriving instances Typeable1, Typeable2, etc ----------------------------------------------+---------------------------- Reporter: maeder | Owner: Type: task | Status: closed Priority: normal | Milestone: Component: Compiler | Version: Resolution: wontfix | 7.8.1-rc1 Operating System: Unknown/Multiple | Keywords: Type of failure: GHC rejects valid program | Architecture: Test Case: | Unknown/Multiple Blocking: | Difficulty: Unknown | Blocked By: | Related Tickets: ----------------------------------------------+---------------------------- Comment (by dreixel): Replying to [comment:7 maeder]:
The other simple alternative is to patch the renamer and rename the class Data.Typeable.TypeableN to Data.Typeable.Typeable.
This surely does not reconcile typeOF and typeRep, but hand-written instances have been (sort of) deprecated long before.
I'm not familiar with the internals of Data.Typeable
Furthermore, Data.!OldTypeable should be removed. It's more harmful to
Well, I am, and I couldn't find an acceptable solution. But, as I said before, I would very much welcome a better solution. It does have to be fully worked out so that we can judge whether it actually works or not. So please provide a replacement `Data.Typeable` that is better than the current one. provide a second incompatible Typeable class. This was provided as a quick way to make old code compile by simply changing the import. It's marked as deprecated, and while it may not be entirely useful because `OldTypeable` and (New)`Typeable` instances are distinct, it can still make some old code work. I don't see it as harmful, but, again, I'm willing to be convinced otherwise. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/8813#comment:8 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler
#8813: further support deriving instances Typeable1, Typeable2, etc ----------------------------------------------+---------------------------- Reporter: maeder | Owner: Type: task | Status: closed Priority: normal | Milestone: Component: Compiler | Version: Resolution: wontfix | 7.8.1-rc1 Operating System: Unknown/Multiple | Keywords: Type of failure: GHC rejects valid program | Architecture: Test Case: | Unknown/Multiple Blocking: | Difficulty: Unknown | Blocked By: | Related Tickets: ----------------------------------------------+---------------------------- Comment (by maeder): I quick test of adding a Typeable2 class ended with: {{{ libraries/base/Data/Typeable/TypeableN.hs:1:1: Typeable instances can only be derived; replace the following instance: instance [overlap ok] Typeable2 a => Typeable a -- Defined at libraries/base/Data/Typeable/TypeableN.hs:32:10 }}} So, at least, we do not need to worry about hand-written instances. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/8813#comment:9 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler
#8813: further support deriving instances Typeable1, Typeable2, etc ----------------------------------------------+---------------------------- Reporter: maeder | Owner: Type: task | Status: closed Priority: normal | Milestone: Component: Compiler | Version: Resolution: wontfix | 7.8.1-rc1 Operating System: Unknown/Multiple | Keywords: Type of failure: GHC rejects valid program | Architecture: Test Case: | Unknown/Multiple Blocking: | Difficulty: Unknown | Blocked By: | Related Tickets: ----------------------------------------------+---------------------------- Comment (by maeder): http://hackage.haskell.org/package/uni-graphs-2.2.1.0/docs/Graphs- GraphDisp.html contains an example where replacing Typeable1 by Typeable was not enough, because Typeable1 used to fix the kind. I had to add {{{ +{-# LANGUAGE KindSignatures #-} }}} and replace the empty class as follows: {{{ -class Typeable1 nodeType => NodeTypeClass nodeType +class Typeable (nodeType :: * -> *) => NodeTypeClass nodeType }}} So it would make sense to further supply Typeable1, Typeable2, etc. classes with matching kinds. Is there a way to circumvent the above "instances can only be derived" error? Is there a different way to supply TypeableN classes that imply/derive Typeable instances? -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/8813#comment:10 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler
#8813: further support deriving instances Typeable1, Typeable2, etc ----------------------------------------------+---------------------------- Reporter: maeder | Owner: Type: task | Status: closed Priority: normal | Milestone: Component: Compiler | Version: Resolution: wontfix | 7.8.1-rc1 Operating System: Unknown/Multiple | Keywords: Type of failure: GHC rejects valid program | Architecture: Test Case: | Unknown/Multiple Blocking: | Difficulty: Unknown | Blocked By: | Related Tickets: ----------------------------------------------+---------------------------- Comment (by rwbarton): Well, I think this is a bit silly—you should just write the kind signature and forget that `Typeable1` ever existed. However, this does appear to work (with `ConstraintKinds`): {{{ type Typeable1 (t :: * -> *) = Typeable t class Typeable1 t => C t -- *Main> :k C -- C :: (* -> *) -> Constraint }}} so I suppose `Data.Typeable` could export such type synonyms `Typeable1`, etc. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/8813#comment:11 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler
#8813: further support deriving instances Typeable1, Typeable2, etc ----------------------------------------------+---------------------------- Reporter: maeder | Owner: Type: task | Status: closed Priority: normal | Milestone: Component: Compiler | Version: Resolution: wontfix | 7.8.1-rc1 Operating System: Unknown/Multiple | Keywords: Type of failure: GHC rejects valid program | Architecture: Test Case: | Unknown/Multiple Blocking: | Difficulty: Unknown | Blocked By: | Related Tickets: ----------------------------------------------+---------------------------- Comment (by maeder): I'm confused. Can _class_ synonyms be introduced using the keyword "type"? -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/8813#comment:12 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler
#8813: further support deriving instances Typeable1, Typeable2, etc ----------------------------------------------+---------------------------- Reporter: maeder | Owner: Type: task | Status: closed Priority: normal | Milestone: Component: Compiler | Version: Resolution: wontfix | 7.8.1-rc1 Operating System: Unknown/Multiple | Keywords: Type of failure: GHC rejects valid program | Architecture: Test Case: | Unknown/Multiple Blocking: | Difficulty: Unknown | Blocked By: | Related Tickets: ----------------------------------------------+---------------------------- Comment (by carter): @maeder 1) this ticket is closed 2) if you're having trouble understanding how to work around this, please email haskell-cafe with questions, or ask for help on #haskell on freenode 3) you can use CPP + Reid's suggestion of constraint kinds (http://blog .omega-prime.co.uk/?p=127 is a blog post on them) to emulate having Typeable1 ... N conditionally defined as non polykinded alternatives using constraint kinds. This seems to be more work than just fixing the code mind you :) 4) if you're confused about constraint kinds, ask on haskell cafe mailing list or on #haskell on freenode -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/8813#comment:13 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler
#8813: further support deriving instances Typeable1, Typeable2, etc ----------------------------------------------+---------------------------- Reporter: maeder | Owner: Type: task | Status: new Priority: normal | Milestone: Component: Compiler | Version: Resolution: | 7.8.1-rc1 Operating System: Unknown/Multiple | Keywords: Type of failure: GHC rejects valid program | Architecture: Test Case: | Unknown/Multiple Blocking: | Difficulty: Unknown | Blocked By: | Related Tickets: ----------------------------------------------+---------------------------- Changes (by maeder): * status: closed => new * resolution: wontfix => Comment: If you have such a simple workaround based on !ConstraintKinds why do you break backwards-compatibility nilly-willy at let me waste my time by asking for a patch? -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/8813#comment:14 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler
#8813: further support deriving instances Typeable1, Typeable2, etc ----------------------------------------------+---------------------------- Reporter: maeder | Owner: Type: task | Status: new Priority: normal | Milestone: Component: Compiler | Version: Resolution: | 7.8.1-rc1 Operating System: Unknown/Multiple | Keywords: Type of failure: GHC rejects valid program | Architecture: Test Case: | Unknown/Multiple Blocking: | Difficulty: Unknown | Blocked By: | Related Tickets: ----------------------------------------------+---------------------------- Comment (by simonpj): Guys, lets all be polite! Christian, yes indeed one of the primary motivations for `-XConstraintKinds` was to allow "type" synonyms to include class constraints (and indeed all sorts of constraints). Pedro said "I couldn't find an acceptable solution. But, as I said before, I would very much welcome a better solution." Reid suggested one, perhaps one that Pedro thought of and discarded, perhaps not. It has the advantage that it might be a simple change to `Data.Typeable` making (deprecated) exports of `Typeable1`, `Typeable2` etc. Pedro: can you think of any problems with this? Thanks Reid. If someone would like to try it out and send a patch the validates, it might just make it into 7.8. Simon -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/8813#comment:15 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler
#8813: further support deriving instances Typeable1, Typeable2, etc ----------------------------------------------+---------------------------- Reporter: maeder | Owner: Type: task | Status: new Priority: normal | Milestone: Component: Compiler | Version: Resolution: | 7.8.1-rc1 Operating System: Unknown/Multiple | Keywords: Type of failure: GHC rejects valid program | Architecture: Test Case: | Unknown/Multiple Blocking: | Difficulty: Unknown | Blocked By: | Related Tickets: ----------------------------------------------+---------------------------- Comment (by maeder): I've only added Typeable1 and Typeable2 and did not try to reduce the language extensions required in the attached modules Data.Typeable and Data.Typeable.TypeableN. I even think, these synonyms should not be deprecated since they help useres to avoid kind signatures! -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/8813#comment:16 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler
#8813: further support deriving instances Typeable1, Typeable2, etc ----------------------------------------------+---------------------------- Reporter: maeder | Owner: Type: task | Status: new Priority: normal | Milestone: Component: Compiler | Version: Resolution: | 7.8.1-rc1 Operating System: Unknown/Multiple | Keywords: Type of failure: GHC rejects valid program | Architecture: Test Case: | Unknown/Multiple Blocking: | Difficulty: Unknown | Blocked By: | Related Tickets: ----------------------------------------------+---------------------------- Comment (by maeder): These constraint kinds will probably not help for i.e. {{{ deriving instance Typeable2 Gr }}} Sigh. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/8813#comment:17 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler
#8813: further support deriving instances Typeable1, Typeable2, etc ----------------------------------------------+---------------------------- Reporter: maeder | Owner: Type: task | Status: new Priority: normal | Milestone: Component: Compiler | Version: Resolution: | 7.8.1-rc1 Operating System: Unknown/Multiple | Keywords: Type of failure: GHC rejects valid program | Architecture: Test Case: | Unknown/Multiple Blocking: | Difficulty: Unknown | Blocked By: | Related Tickets: ----------------------------------------------+---------------------------- Comment (by kosmikus): I think that even if `TypeableN` would be added as `type` synonyms using `-XConstraintKinds`, they should be deprecated. They're ugly and don't add anything except (a limited amount of) backwards compatibility. Adding a kind-signature in a case that'd otherwise be "too" polymorphic is much clearer IMHO. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/8813#comment:18 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler
#8813: further support deriving instances Typeable1, Typeable2, etc ----------------------------------------------+---------------------------- Reporter: maeder | Owner: Type: task | Status: new Priority: normal | Milestone: Component: Compiler | Version: Resolution: | 7.8.1-rc1 Operating System: Unknown/Multiple | Keywords: Type of failure: GHC rejects valid program | Architecture: Test Case: | Unknown/Multiple Blocking: | Difficulty: Unknown | Blocked By: | Related Tickets: ----------------------------------------------+---------------------------- Comment (by rwbarton): Christian: actually that does work. That seems like a decent argument to include these type synonyms for backwards-compatibility purposes. (As kosmikus notes, they're still not 100% backwards compatible. For example, `Typeable` still doesn't fix the kind of its argument, which could matter in a module with `PolyKinds`; and since `TypeableN` is now a type synonym it can't be the argument to another type constructor (with `ConstraintKinds`). But those are both fairly obscure cases.) I fully agree though that the type synonyms should be marked as deprecated. `TypeableN` is a hack that served its purpose; now we can express our programs better using orthogonal features (polykinded types and kind signatures). -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/8813#comment:19 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler
#8813: further support deriving instances Typeable1, Typeable2, etc ----------------------------------------------+---------------------------- Reporter: maeder | Owner: Type: task | Status: new Priority: normal | Milestone: Component: Compiler | Version: Resolution: | 7.8.1-rc1 Operating System: Unknown/Multiple | Keywords: Type of failure: GHC rejects valid program | Architecture: Test Case: | Unknown/Multiple Blocking: | Difficulty: Unknown | Blocked By: | Related Tickets: ----------------------------------------------+---------------------------- Comment (by maeder): Ok, deprecate them. When they are finally gone users could add such synonyms later themselves to easily port their old code. (The release notes should refer to solutions using !KindSignatures and !ConstraintKinds.) -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/8813#comment:20 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler
#8813: further support deriving instances Typeable1, Typeable2, etc ----------------------------------------------+---------------------------- Reporter: maeder | Owner: Type: task | Status: new Priority: normal | Milestone: Component: Compiler | Version: Resolution: | 7.8.1-rc1 Operating System: Unknown/Multiple | Keywords: Type of failure: GHC rejects valid program | Architecture: Test Case: | Unknown/Multiple Blocking: | Difficulty: Unknown | Blocked By: | Related Tickets: ----------------------------------------------+---------------------------- Comment (by maeder): The new module Data.Typeable.TypeableN must also be added to base.cabal, as I just realised. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/8813#comment:21 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler
#8813: further support deriving instances Typeable1, Typeable2, etc ----------------------------------------------+---------------------------- Reporter: maeder | Owner: Type: task | Status: new Priority: normal | Milestone: Component: Compiler | Version: Resolution: | 7.8.1-rc1 Operating System: Unknown/Multiple | Keywords: Type of failure: GHC rejects valid program | Architecture: Test Case: | Unknown/Multiple Blocking: | Difficulty: Unknown | Blocked By: | Related Tickets: ----------------------------------------------+---------------------------- Comment (by rwbarton): I would suggest just adding them to Data.Typeable; wouldn't that allow most uses of Data.Typeable to remain unchanged in 7.8? -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/8813#comment:22 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler
#8813: further support deriving instances Typeable1, Typeable2, etc ----------------------------------------------+---------------------------- Reporter: maeder | Owner: Type: task | Status: new Priority: normal | Milestone: Component: Compiler | Version: Resolution: | 7.8.1-rc1 Operating System: Unknown/Multiple | Keywords: Type of failure: GHC rejects valid program | Architecture: Test Case: | Unknown/Multiple Blocking: | Difficulty: Unknown | Blocked By: | Related Tickets: ----------------------------------------------+---------------------------- Comment (by maeder): I don't mind. I just thought it is easier to simply remove the import (and export entries) later on, but ignored the burden of adding and removing files. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/8813#comment:23 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler
#8813: further support deriving instances Typeable1, Typeable2, etc ----------------------------------------------+---------------------------- Reporter: maeder | Owner: Type: task | Status: new Priority: normal | Milestone: Component: Compiler | Version: Resolution: | 7.8.1-rc1 Operating System: Unknown/Multiple | Keywords: Type of failure: GHC rejects valid program | Architecture: Test Case: | Unknown/Multiple Blocking: | Difficulty: Unknown | Blocked By: | Related Tickets: ----------------------------------------------+---------------------------- Comment (by simonpj): Pedro, any comments about this? Simon -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/8813#comment:24 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler
#8813: further support deriving instances Typeable1, Typeable2, etc ----------------------------------------------+---------------------------- Reporter: maeder | Owner: Type: task | Status: new Priority: normal | Milestone: Component: Compiler | Version: Resolution: | 7.8.1-rc1 Operating System: Unknown/Multiple | Keywords: Type of failure: GHC rejects valid program | Architecture: Test Case: | Unknown/Multiple Blocking: | Difficulty: Unknown | Blocked By: | Related Tickets: ----------------------------------------------+---------------------------- Comment (by dreixel): Yes, I'm working on it, will comment later today. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/8813#comment:25 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler
#8813: further support deriving instances Typeable1, Typeable2, etc ----------------------------------------------+---------------------------- Reporter: maeder | Owner: dreixel Type: task | Status: new Priority: normal | Milestone: Component: Compiler | Version: Resolution: | 7.8.1-rc1 Operating System: Unknown/Multiple | Keywords: Type of failure: GHC rejects valid program | Architecture: Test Case: | Unknown/Multiple Blocking: | Difficulty: Unknown | Blocked By: | Related Tickets: ----------------------------------------------+---------------------------- Changes (by dreixel): * owner: => dreixel -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/8813#comment:26 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler
#8813: further support deriving instances Typeable1, Typeable2, etc
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Reporter: maeder | Owner: dreixel
Type: task | Status: new
Priority: normal | Milestone:
Component: Compiler | Version:
Resolution: | 7.8.1-rc1
Operating System: Unknown/Multiple | Keywords:
Type of failure: GHC rejects valid program | Architecture:
Test Case: | Unknown/Multiple
Blocking: | Difficulty: Unknown
| Blocked By:
| Related Tickets:
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Comment (by Jose Pedro Magalhaes
Pedro said "I couldn't find an acceptable solution. But, as I said before, I would very much welcome a better solution." Reid suggested one,
#8813: further support deriving instances Typeable1, Typeable2, etc ----------------------------------------------+---------------------------- Reporter: maeder | Owner: dreixel Type: task | Status: merge Priority: normal | Milestone: Component: Compiler | Version: Resolution: | 7.8.1-rc1 Operating System: Unknown/Multiple | Keywords: Type of failure: GHC rejects valid program | Architecture: Test Case: | Unknown/Multiple Blocking: | Difficulty: Unknown | Blocked By: | Related Tickets: ----------------------------------------------+---------------------------- Changes (by dreixel): * status: new => merge Comment: Replying to [comment:15 simonpj]: perhaps one that Pedro thought of and discarded, perhaps not. It has the advantage that it might be a simple change to `Data.Typeable` making (deprecated) exports of `Typeable1`, `Typeable2` etc.
Pedro: can you think of any problems with this? Thanks Reid.
No, I hadn't thought of this before, and no, I don't see any problems with it. As has been pointed out already, it won't work for all old code. But it might still make some more code work, and I don't see a problem with including it. So I submitted a patch to base adding those. In particular, the original problem code described in this ticket should now compile (along with a deprecation warning). I've also updated the wiki page at https://ghc.haskell.org/trac/ghc/wiki/GhcKinds/PolyTypeable to refer to 7.8 as the present, not the future, and I've added a section on how to make your code compile again. I've also added a link to this wiki page from the Data.Typeable haddock. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/8813#comment:28 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler
#8813: further support deriving instances Typeable1, Typeable2, etc ----------------------------------------------+---------------------------- Reporter: maeder | Owner: dreixel Type: task | Status: merge Priority: normal | Milestone: Component: Compiler | Version: Resolution: | 7.8.1-rc1 Operating System: Unknown/Multiple | Keywords: Type of failure: GHC rejects valid program | Architecture: Test Case: | Unknown/Multiple Blocking: | Difficulty: Unknown | Blocked By: | Related Tickets: ----------------------------------------------+---------------------------- Comment (by simonpj): Pedro: Fantastic, thank you. Did you run validate? Austin: please merge to the stable branch. Reid: thank you for the idea! Christian: I hope this makes things better for you. Simon -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/8813#comment:29 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler
#8813: further support deriving instances Typeable1, Typeable2, etc ----------------------------------------------+---------------------------- Reporter: maeder | Owner: dreixel Type: task | Status: merge Priority: normal | Milestone: Component: Compiler | Version: Resolution: | 7.8.1-rc1 Operating System: Unknown/Multiple | Keywords: Type of failure: GHC rejects valid program | Architecture: Test Case: | Unknown/Multiple Blocking: | Difficulty: Unknown | Blocked By: | Related Tickets: ----------------------------------------------+---------------------------- Comment (by dreixel): Replying to [comment:29 simonpj]:
Pedro: Fantastic, thank you. Did you run validate?
Yes, it passed. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/8813#comment:30 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler
#8813: further support deriving instances Typeable1, Typeable2, etc ----------------------------------------------+---------------------------- Reporter: maeder | Owner: dreixel Type: task | Status: merge Priority: normal | Milestone: Component: Compiler | Version: Resolution: | 7.8.1-rc1 Operating System: Unknown/Multiple | Keywords: Type of failure: GHC rejects valid program | Architecture: Test Case: | Unknown/Multiple Blocking: | Difficulty: Unknown | Blocked By: | Related Tickets: ----------------------------------------------+---------------------------- Comment (by maeder): Thanks, guys, I hope this makes things better also for other (less language extensions aware) users. Christian -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/8813#comment:31 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler
#8813: further support deriving instances Typeable1, Typeable2, etc ----------------------------------------------+---------------------------- Reporter: maeder | Owner: dreixel Type: task | Status: merge Priority: normal | Milestone: Component: Compiler | Version: Resolution: | 7.8.1-rc1 Operating System: Unknown/Multiple | Keywords: Type of failure: GHC rejects valid program | Architecture: Test Case: | Unknown/Multiple Blocking: | Difficulty: Unknown | Blocked By: | Related Tickets: ----------------------------------------------+---------------------------- Comment (by maeder): looking at `Data/Typeable/Internal.hs` in the above patch I see that there are two blocks of language extension pragmas, before and after the haddock header, which is a bit confusing as I expected !ConstraintKinds to be near !KindSignatures. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/8813#comment:32 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler
#8813: further support deriving instances Typeable1, Typeable2, etc
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Reporter: maeder | Owner: dreixel
Type: task | Status: merge
Priority: normal | Milestone:
Component: Compiler | Version:
Resolution: | 7.8.1-rc1
Operating System: Unknown/Multiple | Keywords:
Type of failure: GHC rejects valid program | Architecture:
Test Case: | Unknown/Multiple
Blocking: | Difficulty: Unknown
| Blocked By:
| Related Tickets:
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Comment (by Jose Pedro Magalhaes
#8813: further support deriving instances Typeable1, Typeable2, etc ----------------------------------------------+---------------------------- Reporter: maeder | Owner: dreixel Type: task | Status: merge Priority: normal | Milestone: Component: Compiler | Version: Resolution: | 7.8.1-rc1 Operating System: Unknown/Multiple | Keywords: Type of failure: GHC rejects valid program | Architecture: Test Case: | Unknown/Multiple Blocking: | Difficulty: Unknown | Blocked By: | Related Tickets: ----------------------------------------------+---------------------------- Comment (by dreixel): Oh, yes. Fixed, thanks. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/8813#comment:34 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler
#8813: further support deriving instances Typeable1, Typeable2, etc ----------------------------------------------+---------------------------- Reporter: maeder | Owner: dreixel Type: task | Status: merge Priority: normal | Milestone: Component: Compiler | Version: Resolution: | 7.8.1-rc1 Operating System: Unknown/Multiple | Keywords: Type of failure: GHC rejects valid program | Architecture: Test Case: | Unknown/Multiple Blocking: | Difficulty: Unknown | Blocked By: | Related Tickets: ----------------------------------------------+---------------------------- Comment (by maeder): Thanks and sorry again, but should not all language pragmas be on top of the file (before the haddock header)? -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/8813#comment:35 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler
#8813: further support deriving instances Typeable1, Typeable2, etc ----------------------------------------------+---------------------------- Reporter: maeder | Owner: dreixel Type: task | Status: merge Priority: normal | Milestone: Component: Compiler | Version: Resolution: | 7.8.1-rc1 Operating System: Unknown/Multiple | Keywords: Type of failure: GHC rejects valid program | Architecture: Test Case: | Unknown/Multiple Blocking: | Difficulty: Unknown | Blocked By: | Related Tickets: ----------------------------------------------+---------------------------- Comment (by dreixel): I'm not sure why the `Unsafe` is separate. I guess that was added during some `SafeHaskell` sweep. I'd prefer if they are all together, yes, but that should probably be done in one go to all the modules in base, at least (I suspect `Data.Typeable.Internal` might not be the only module with this problem...) -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/8813#comment:36 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler
#8813: further support deriving instances Typeable1, Typeable2, etc ----------------------------------------------+---------------------------- Reporter: maeder | Owner: dreixel Type: task | Status: merge Priority: normal | Milestone: Component: Compiler | Version: Resolution: | 7.8.1-rc1 Operating System: Unknown/Multiple | Keywords: Type of failure: GHC rejects valid program | Architecture: Test Case: | Unknown/Multiple Blocking: | Difficulty: Unknown | Blocked By: | Related Tickets: ----------------------------------------------+---------------------------- Comment (by maeder): `Unsafe` being separate at the top of the file actually suggests that all language pragmas should be on top of the file. (But that's a subject of a style guide.) -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/8813#comment:37 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler
#8813: further support deriving instances Typeable1, Typeable2, etc ----------------------------------------------+---------------------------- Reporter: maeder | Owner: dreixel Type: task | Status: merge Priority: normal | Milestone: Component: Compiler | Version: Resolution: | 7.8.1-rc1 Operating System: Unknown/Multiple | Keywords: Type of failure: GHC rejects valid program | Architecture: Test Case: | Unknown/Multiple Blocking: | Difficulty: Unknown | Blocked By: | Related Tickets: ----------------------------------------------+---------------------------- Comment (by dreixel): Yes. That should be a separate ticket, though. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/8813#comment:38 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler
#8813: further support deriving instances Typeable1, Typeable2, etc
----------------------------------------------+----------------------------
Reporter: maeder | Owner: dreixel
Type: task | Status: closed
Priority: normal | Milestone:
Component: Compiler | Version:
Resolution: fixed | 7.8.1-rc1
Operating System: Unknown/Multiple | Keywords:
Type of failure: GHC rejects valid program | Architecture:
Test Case: | Unknown/Multiple
Blocking: | Difficulty: Unknown
| Blocked By:
| Related Tickets:
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Changes (by hvr):
* status: merge => closed
* resolution: => fixed
Comment:
Replying to [comment:27 Jose Pedro Magalhaes
In [changeset:"a5383f7400d05a758094578da28d958fb694b726/base"]: {{{ #!CommitTicketReference repository="base" revision="a5383f7400d05a758094578da28d958fb694b726" Provide Typeable1..7 as type synonyms (see #8813) }}}
This has been merged in the ghc-7.8 branch via [84aad16f054fe8c7b/base] Is there anything left to be done for the release notes? -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/8813#comment:39 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler
#8813: further support deriving instances Typeable1, Typeable2, etc ----------------------------------------------+---------------------------- Reporter: maeder | Owner: dreixel Type: task | Status: closed Priority: normal | Milestone: 7.8.1 Component: libraries/base | Version: Resolution: fixed | 7.8.1-rc1 Operating System: Unknown/Multiple | Keywords: Type of failure: GHC rejects valid program | Architecture: Test Case: | Unknown/Multiple Blocking: | Difficulty: Unknown | Blocked By: | Related Tickets: ----------------------------------------------+---------------------------- Changes (by hvr): * component: Compiler => libraries/base * milestone: => 7.8.1 -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/8813#comment:40 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler
#8813: further support deriving instances Typeable1, Typeable2, etc ----------------------------------------------+---------------------------- Reporter: maeder | Owner: dreixel Type: task | Status: closed Priority: normal | Milestone: 7.8.1 Component: libraries/base | Version: Resolution: fixed | 7.8.1-rc1 Operating System: Unknown/Multiple | Keywords: Type of failure: GHC rejects valid program | Architecture: Test Case: | Unknown/Multiple Blocking: | Difficulty: Unknown | Blocked By: | Related Tickets: ----------------------------------------------+---------------------------- Comment (by George): It seems this fix might allow quickspec to compile unmodified in RC2. In RC1 it fails with {{{ [ 3 of 20] Compiling Test.QuickSpec.Utils.Typeable ( src/Test/QuickSpec/Utils/Typeable.hs, dist/build/Test/QuickSpec/Utils/Typeable.o ) src/Test/QuickSpec/Utils/Typeable.hs:9:59: Not in scope: type constructor or class ‛T.Typeable1’ Perhaps you meant ‛T.Typeable’ (imported from Data.Typeable) src/Test/QuickSpec/Utils/Typeable.hs:9:72: Not in scope: type constructor or class ‛T.Typeable2’ Perhaps you meant ‛T.Typeable’ (imported from Data.Typeable) Failed to install quickspec-0.9.2 }}} Just thought you might want to know of examples where this fix is indeed helpful -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/8813#comment:41 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler
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