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<p class="MsoNormal" style="margin-left:36.0pt">I suppose we want an instance<br>
forall k. instance Typeable (k -> *) (Proxy k)<br>
<br>
<span style="font-size:11.0pt;font-family:"Verdana","sans-serif";color:#1F497D"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Verdana","sans-serif";color:#1F497D">Yes, that looks right.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Verdana","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal" style="margin-left:36.0pt">So the universally quantified kind variables of the tycon should end up universally<br>
quantified in the instance as well. How does this translate to the ds_tvs, ds_tys, and<br>
ds_tc_args arguments of a DerivSpec<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Verdana","sans-serif";color:#1F497D">My instinct is that the ds_tvs include both type and kind variables, kind variables first. The kinds of the type variables can mention the kind variables.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Verdana","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Verdana","sans-serif";color:#1F497D">The ds_tys field shoud include kind arguments as well as type arguments.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Verdana","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Verdana","sans-serif";color:#1F497D">Does that work?<br>
<br>
Simon<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Verdana","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
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<p class="MsoNormal"><b><span lang="EN-US" style="font-size:10.0pt;font-family:"Tahoma","sans-serif"">From:</span></b><span lang="EN-US" style="font-size:10.0pt;font-family:"Tahoma","sans-serif""> josepedromagalhaes@gmail.com [mailto:josepedromagalhaes@gmail.com]
<b>On Behalf Of </b>José Pedro Magalhães<br>
<b>Sent:</b> 19 February 2013 10:04<br>
<b>To:</b> ghc-devs@haskell.org; Simon Peyton-Jones<br>
<b>Subject:</b> Fwd: [GHC] #7704: Phantom types break new polykind Typeable with either StandaloneDeriving or AutoDeriveTypeable<o:p></o:p></span></p>
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<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal" style="margin-bottom:12.0pt">Hi Simon,<br>
<br>
How should an instance of Typeable for a polykinded tycon look like? E.g. if we have<br>
<br>
data Proxy (a :: k) = Proxy<br>
-- Proxy :: forall (k :: BOX). k -> *<br>
<br>
I suppose we want an instance<br>
<br>
forall k. instance Typeable (k -> *) (Proxy k)<br>
<br>
Right? So the universally quantified kind variables of the tycon should end up universally<br>
quantified in the instance as well. How does this translate to the ds_tvs, ds_tys, and<br>
ds_tc_args arguments of a DerivSpec?...<br>
<br>
<br>
Thanks,<br>
Pedro<o:p></o:p></p>
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<p class="MsoNormal">---------- Forwarded message ----------<br>
From: <b>GHC</b> <<a href="mailto:cvs-ghc@haskell.org">cvs-ghc@haskell.org</a>><br>
Date: Mon, Feb 18, 2013 at 8:42 PM<br>
Subject: [GHC] #7704: Phantom types break new polykind Typeable with either StandaloneDeriving or AutoDeriveTypeable<br>
To: <br>
Cc: <a href="mailto:ghc-tickets@haskell.org">ghc-tickets@haskell.org</a><br>
<br>
<br>
#7704: Phantom types break new polykind Typeable with either StandaloneDeriving or<br>
AutoDeriveTypeable<br>
-----------------------------+----------------------------------------------<br>
Reporter: nwf | Owner:<br>
Type: bug | Status: new<br>
Priority: normal | Component: Compiler<br>
Version: 7.7 | Keywords:<br>
Os: Unknown/Multiple | Architecture: Unknown/Multiple<br>
Failure: None/Unknown | Blockedby:<br>
Blocking: | Related:<br>
-----------------------------+----------------------------------------------<br>
This test program, reduced from an attempt to bring ekmett's tagged<br>
package to HEAD,<br>
{{{<br>
{-# LANGUAGE DeriveDataTypeable #-}<br>
{-# LANGUAGE PolyKinds #-}<br>
{-# LANGUAGE AutoDeriveTypeable #-}<br>
<br>
newtype Tagged s b = Tagged { unTagged :: b }<br>
}}}<br>
results in<br>
{{{<br>
GHCi, version 7.7.20130218: <a href="http://www.haskell.org/ghc/" target="_blank">
http://www.haskell.org/ghc/</a> :? for help<br>
Loading package ghc-prim ... linking ... done.<br>
Loading package integer-gmp ... linking ... done.<br>
Loading package base ... linking ... done.<br>
[1 of 1] Compiling Main ( typeable.hs, interpreted )<br>
<br>
typeable.hs:5:1:<br>
Derived typeable instance must be of form (Typeable Tagged)<br>
In the stand-alone deriving instance for<br>
`Data.Typeable.Internal.Typeable Tagged'<br>
}}}<br>
<br>
This message is also emitted if I replace `AutoDeriveTypeable`<br>
`StandaloneDeriving` and `deriving instance Typeable Tagged`.<br>
<br>
However, a "deriving (Typeable)" clause on the newtype definition works<br>
just fine.<br>
<span style="color:#888888"><br>
<span class="hoenzb">--</span><br>
<span class="hoenzb">Ticket URL: <<a href="http://hackage.haskell.org/trac/ghc/ticket/7704" target="_blank">http://hackage.haskell.org/trac/ghc/ticket/7704</a>></span><br>
<span class="hoenzb">GHC <<a href="http://www.haskell.org/ghc/" target="_blank">http://www.haskell.org/ghc/</a>></span><br>
<span class="hoenzb">The Glasgow Haskell Compiler</span><br>
<br>
<span class="hoenzb">_______________________________________________</span><br>
<span class="hoenzb">ghc-tickets mailing list</span><br>
<span class="hoenzb"><a href="mailto:ghc-tickets@haskell.org">ghc-tickets@haskell.org</a></span><br>
<span class="hoenzb"><a href="http://www.haskell.org/mailman/listinfo/ghc-tickets" target="_blank">http://www.haskell.org/mailman/listinfo/ghc-tickets</a></span></span><o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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