[Haskell-cafe] Proposal: Shorter Import Syntax
acowley at seas.upenn.edu
Thu Jun 4 22:04:21 UTC 2015
> On Jun 4, 2015, at 5:41 PM, Brandon Allbery <allbery.b at gmail.com> wrote:
>> On Thu, Jun 4, 2015 at 5:36 PM, Anthony Cowley <acowley at seas.upenn.edu> wrote:
>> > On Jun 4, 2015, at 5:22 PM, Herbert Valerio Riedel <hvr at gnu.org> wrote:
>> > new syntax, Cabal has no way to know that a new language syntax is
>> > required and that thereby needs exclude (not implemented yet) the
>> > affected package versions from the install-plan configuration space.
>> I can't parse your last sentence. The proposed syntax is currently a parse error, so a package that used it could depend on a GHC new enough to support it (eg with a base version constraint). No older packages would cause any errors whatsoever.
> Your unstated assumption is that everyone always has the latest ghc.
> How do people who are on, say, Debian or CentOS, deal with a language change that is not compatible with their compiler? How does cabal avoid pulling in package versions using the new incompatible syntax?
I guess I'm just not familiar with how Debian and CentOS work, because this doesn't seem like a change to me, but you and hvr have much more experience than I do. How do those systems deal with a package that has a lower bound on base?
If I require base >= 7.9, does that get thrown out to work with GHC 7.4? How does that work?
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