[Haskell] Module system question

Simon Peyton-Jones simonpj at microsoft.com
Wed Oct 17 03:35:22 EDT 2007

[Moving to haskell-prime]

I think there would be real merit in some reworking of the module system, especially to allow programmers to give the complete signature of a module, perhaps by expanding what the export list says.  Including instances.

Any such thing is very far from being a tried-and-tested feature, though, and it'd be hard to argue it into Haskell' unless someone gets busy very soon.  Even then it looks a bit late.


| -----Original Message-----
| From: haskell-bounces at haskell.org [mailto:haskell-bounces at haskell.org] On Behalf Of John Meacham
| Sent: 17 October 2007 03:00
| To: haskell at haskell.org
| Subject: Re: [Haskell] Module system question
| On Mon, Oct 15, 2007 at 10:34:37PM +0300, Iavor Diatchki wrote:
| > I like the Hugs behavior because it accepts more programs.  OTOH,
| > GHC's behavior may be a bit simpler to explain and implement(?).   Any
| > thoughts?
| Currently, the class and datatype namespaces are considered the same by
| the standard. There is no particular reason this needs to be the case as
| they can always be disambiguated syntactically except in the one case of
| export/import lists. Some of the proposed module system changes for
| haskell' address this issue, which would allow fully separate namespaces
| for the two.
| Although I am not sure exactly what form it will take, I would like some
| reworking of the module system to allow this change in haskell'. There
| are some concrete proposals on the wiki, I have been meaning to make a
| grand unified proposal at some point that incorperates all the proposed
| changes (and incidentally, more importantly, proves compatibility
| between them) to the module system so that we may consider it. Not that
| I think all the proposals should go in or not as a unit, but it will
| give us a concrete theoretically implementable superset of all the
| proposals to think about and illuminate any interactions between
| proposals that might not be obvious when considered separately.
|         John
| --
| John Meacham - ⑆repetae.net⑆john⑈
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