Hs-boot files tend to get in the way of optimisation. Moreover, sometimes they are truly necessary, and if there are un-necessary ones that can greatly complicate adding necessary ones. There are already LOTS of data types declared as instances of Typeable at the place that Typeable class is defined; no harm in one more.
So I'd really prefer the re-jig if that's ok Simon | -----Original Message----- | From: Richard Eisenberg [mailto:e...@cis.upenn.edu] | Sent: 24 July 2013 22:37 | To: Simon Peyton-Jones | Cc: ghc-devs@haskell.org | Subject: Re: [commit: base] master: Implement "TypeLevelReasoning" proposal | at wiki:TypeLevelReasoning (365b9d8) | | I agree that hs-boot files are a little inelegant, but is there a bigger problem with | them? I consider instances to be more tied to a datatype definition than the class | definition. It may be possible (I think it is) to avoid the Proxy.hs-boot and | Equality.hs-boot files if we scatter their instances across the modules. But, then | the "definition" of these types would be spread across a large surface area. To me, | that makes the types harder to update and perhaps harder to understand (though | haddock does a nice job of collecting all the instance declarations together). | | So, my thought is that the mechanism of hs-boot files may be a little ugly, but it | makes the code (that is, the collection of instances) easier to consider as a whole | and easier to update. That tradeoff seems worthwhile. | | That all said, if you (or others) feel strongly about it, I can rejigger it. | | Richard | | On Jul 24, 2013, at 3:14 PM, Simon Peyton-Jones wrote: | | > Richard I am deeply suspicious of all these hs-boot files. | > | > Instances should preferably go EITHER with the data type declaration OR with | the class declaration. | > | > In the case of Proxy, for example, why can't the Typeable instance for Proxy go | in Data.Typeable.Internals? (And perhaps similarly for other instances.) | > | > Simon | > | > | -----Original Message----- | > | From: ghc-commits [mailto:ghc-commits-boun...@haskell.org] On Behalf Of | > | Richard Eisenberg | > | Sent: 24 July 2013 12:41 | > | To: ghc-comm...@haskell.org | > | Subject: [commit: base] master: Implement "TypeLevelReasoning" proposal | at | > | wiki:TypeLevelReasoning (365b9d8) | > | | > | Repository : http://darcs.haskell.org/ghc.git/ | > | | > | On branch : master | > | | > | | http://hackage.haskell.org/trac/ghc/changeset/365b9d86d195dc483610a68836b4 | > | 063656602244 | > | | > | >--------------------------------------------------------------- | > | | > | commit 365b9d86d195dc483610a68836b4063656602244 | > | Author: Richard Eisenberg <e...@cis.upenn.edu> | > | Date: Wed Jul 24 12:38:50 2013 +0100 | > | | > | Implement "TypeLevelReasoning" proposal at wiki:TypeLevelReasoning | > | | > | This commit includes a propositional equality (:=:) in Data.Type.Equality, | > | a Proxy type in Data.Proxy, and has updates to Typeable. | > | | > | There is an unfortunate number of hs-boot files necessary, but that | > | seems cleaner than moving Typeable instances around willy-nilly. | > | | > | Data/Data.hs | 2 +- | > | Data/Proxy.hs | 129 | > | ++++++++++++++++++++++++++++++++++++++++ | > | Data/Proxy.hs-boot | 5 ++ | > | Data/Type/Equality.hs | 99 | > | ++++++++++++++++++++++++++++++ | > | Data/Type/Equality.hs-boot | 6 ++ | > | Data/Typeable.hs | 42 +++++++------ | > | Data/Typeable/Internal.hs | 5 +- | > | Data/Typeable/Internal.hs-boot | 3 +- | > | base.cabal | 2 + | > | 9 files changed, 269 insertions(+), 24 deletions(-) | > | | > | | > | Diff suppressed because of size. To see it, use: | > | | > | git show 365b9d86d195dc483610a68836b4063656602244 | > | | > | _______________________________________________ | > | ghc-commits mailing list | > | ghc-comm...@haskell.org | > | http://www.haskell.org/mailman/listinfo/ghc-commits | > | > | > | _______________________________________________ ghc-devs mailing list ghc-devs@haskell.org http://www.haskell.org/mailman/listinfo/ghc-devs
