-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 They're not implemented, but they won't be until we decide exactly what they mean - it's not simple. (at least the syntax is obvious: http://hackage.haskell.org/trac/haskell-prime/wiki/PermitSignaturesInExports ) One big question: can their presence have any effect? * on the module doing the exporting (conflict with the presence of in-module type-signature for the same thing; type restriction in-module; monomorphism-restriction-lifting or defaulting-removal of the named thing) * on modules importing this one (can a module re-export something, giving it a more restrictive type-signature?) Case study 1: module Foo1 (Foo(..), foo :: Foo) where data Foo = CFoo foo :: Foo foo = CFoo If we interpret it as an in-module type signature, it will be a problem because there already is one for foo. (unless we should relax the rules for uniqueness of type signatures anyway?) Case study 2: module Foo2 (foo :: Foo) where data Foo = CFoo foo :: Foo foo = CFoo The type doesn't need to be exported. (which is more likely if it's just a type synonym than a new type.) So what scope are the names in the export-list-type-signature drawn from? It would be odd if a type signature couldn't be given because some names weren't exported; but it would be odd if a module-user looking at the interface saw some types that weren't defined anywhere visible. This suggests that wildcards in type signatures could be helpful for this: module Foo3 (foo :: Int -> Foo -> Bool) versus module Foo4 (foo :: Int -> _ -> Bool) Open for discussion. Isaac -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.6 (GNU/Linux) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org iD8DBQFGdmneHgcxvIWYTTURAlTpAJ425ZL8WPzkAeIxRbgGSOQFCKtrnwCeIG0P aawB6GDwSfiRNM20MErBj8E= =KCKj -----END PGP SIGNATURE-----