[Haskell-cafe] Packages and modules
brianh at metamilk.com
Mon Jun 26 13:51:06 EDT 2006
Brian Hulley wrote:
> import Gtk/Widget.Button -- instead of grafting
> In all cases I think it would be an absolute disaster to allow
> modules to be imported without an explicit package id because this
> would defeat the whole purpose of having a simple per-package
> namespace for modules and wouldn't allow the reader of source to know
> which packages it's referring to.
I meant the above only in relaiton to modules in other packages. Modules in
the current package would be identified as they are at the moment, without
any package qualification (since only the compiler command line would know
the name of the current package).
Here is an example of a module before and after applying my proposed syntax
to the source of a module in some hypothetical package called duma:
import Prelude hiding(length, take, drop)
import qualified Prelude as P
import qualified Data.ByteString.Char8 as B
import Base/Prelude hiding(length, take, drop)
import qualified Base/Prelude as P
import qualified Fps/Data.ByteString.Char8 as B
So all that's needed is qualifying the Prelude and ByteString modules by
Base/ and Fps/ respectively and we've gained the advantage of not having to
decide on the name of the actual package (duma) in advance, and also not
having to incorporate this name everywhere as part of the module name within
the source of the duma package itself. Explicit package directives would
only be needed if we wanted to refer to some specific version of a package
package fps-0.6 as Fps
but I'd imagine that usually we want to use the latest version.
With the above syntax I think the only thing that has to be unique are the
package names ie fps-0.6 must always refer to the one and only fast packed
string package otherwise we'd end up with a nightmare of incompatibility
when trying to compile other people's code.
Logic empowers us and Love gives us purpose.
Yet still phantoms restless for eras long past,
congealed in the present in unthought forms,
strive mightily unseen to destroy us.
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