[commit: ghc] master: Allow deriving Typeable for more tycons (92191a3)

[José Pedro Magalhães]

Ok, done now.


Cheers,
Pedro

On Thu, May 16, 2013 at 5:26 PM, Simon Peyton-Jones
<simonpj at microsoft.com>wrote:

>  Oh, it’s easy.  If you know what TyCons are defined in this file (and
> you do, in derivTyDecl), then find the TyCon, and then do****
>
>           [ promoted_dc | Just promoted_dc <- map promoteDataCon_maybe
> (tyConDataCons tc) ]****
>
> ** **
>
> ** **
>
> Simon****
>
> * *
>
> *Microsoft Research Limited (company number 03369488) is registered in
> England and Wales*
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>
> *From:* josepedromagalhaes at gmail.com [mailto:josepedromagalhaes at gmail.com]
> *On Behalf Of *José Pedro Magalhães
> *Sent:* 16 May 2013 10:34
> *To:* Simon Peyton-Jones
> *Cc:* ghc-devs at haskell.org
> *Subject:* Re: [commit: ghc] master: Allow deriving Typeable for more
> tycons (92191a3)****
>
> ** **
>
> Hi Simon,
>
> Yes. I still need to do some more work, though, because one thing is not
> yet working as I would like it
> to. Right now, if you define a datatype with -XDataKinds, you can derive
> Typeable for the promoted
> constructors:****
>
> data N = Z | S N deriving Typeable -- for N
> deriving instance Typeable Z
> deriving instance Typeable S****
>
>
> Note that the last two Typeable instances can only be given by standalone
> deriving. However, in case
> the user specifies -XAutoDeriveTypeable, I would expect all three
> instances to be unnecessary. Right
> now, however, we do not automatically derive Typeable instances for
> promoted constructors. This is
> because they are not tycl_decls (as in makeDerivSpecs in TcDeriv). What's
> the best way to easily
> get hold of all the promoted tycons in a module?
>
>
> Thanks,
> Pedro****
>
> On Wed, May 8, 2013 at 10:37 AM, Simon Peyton-Jones <simonpj at microsoft.com>
> wrote:****
>
> Pedro
>
> Surely should be some user-manual change to go with this?
>
> Simon****
>
>
> | -----Original Message-----
> | From: ghc-commits-bounces at haskell.org [mailto:ghc-commits-
> | bounces at haskell.org] On Behalf Of José Pedro Magalhães
> | Sent: 07 May 2013 13:27
> | To: ghc-commits at haskell.org
> | Subject: [commit: ghc] master: Allow deriving Typeable for more tycons
> | (92191a3)
> |
> | Repository : http://darcs.haskell.org/ghc.git/
> |
> | On branch  : master
> |
> | https://github.com/ghc/ghc/commit/92191a39a59a036fde4de926e2e322a2c50c84
> | cf
> |
> | >---------------------------------------------------------------
> |
> | commit 92191a39a59a036fde4de926e2e322a2c50c84cf
> | Author: Jose Pedro Magalhaes <jpm at cs.ox.ac.uk>
> | Date:   Tue May 7 09:16:29 2013 +0100
> |
> |     Allow deriving Typeable for more tycons
> |
> | >---------------------------------------------------------------
> |
> |  compiler/typecheck/TcDeriv.lhs | 3 ++-
> |  1 file changed, 2 insertions(+), 1 deletion(-)
> |
> | diff --git a/compiler/typecheck/TcDeriv.lhs
> | b/compiler/typecheck/TcDeriv.lhs index 7da30d19b..9b82ed6 100644
> | --- a/compiler/typecheck/TcDeriv.lhs
> | +++ b/compiler/typecheck/TcDeriv.lhs
> | @@ -683,7 +683,8 @@ mkEqnHelp :: CtOrigin -> [TyVar] -> Class -> [Type]
> | -> Type
> |
> |  mkEqnHelp orig tvs cls cls_tys tc_app mtheta
> |    | Just (tycon, tc_args) <- tcSplitTyConApp_maybe tc_app
> | -  , isAlgTyCon tycon    -- Check for functions, primitive types etc
> | +  , className cls == typeableClassName || isAlgTyCon tycon
> | +  -- Avoid functions, primitive types, etc, unless it's Typeable
> |    = mk_alg_eqn tycon tc_args
> |    | otherwise
> |    = failWithTc (derivingThingErr False cls cls_tys tc_app
> |
> |
> |
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