[Haskell-cafe] RE: Packages and modules
simonpj at microsoft.com
Thu Jul 6 11:51:05 EDT 2006
| 1) Qualified names:
| import A.B.C( T1 ) from "foo"
| import A.B.C( T2 ) from "bar"
| type S = A.B.C.T1 -> A.B.C.T2
| I'd suggest that the above should give a compiler error that A.B.C is
| ambiguous (as a qualifier), rather than allowing T1 to disambiguate
| because otherwise it allows people to write code that could be very
| understand ie within the code, every occurrence of A.B.C as a
| should refer to the same module. (Otherwise the thing qualified
| the qualifier that's qualifying it...)
But that's inconsistent with Haskell 98. In H98 you can say
import M( T1 ) as Q
import N( T2 ) as Q
type S = Q.T1 -> Q.T2
and it'll work just fine. You may think it should not work, but that's
water under the bridge. We should be consistent here.
| In my spec, if you omit the package name you get an "old-style" import
| the shared namespace, and if you supply a package name you get a
| import that only searches in the specified package:
| import A.B.C -- search home + exposed as is done at the moment
| import "" A.B.C -- search home package only
| import "pkg" A.B.C -- search "pkg" only
That's exactly what our spec says too. (Good news, again.) Only maybe
not explicitly enough! See the section "Is the from<package>
compulsory". Perhaps you could improve the wording to make it more
Indeed, if we've converged, would you like to fold into our draft
whatever you think is useful from yours?
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