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| author | Simon Marlow <marlowsd@gmail.com> | 2008-08-05 13:35:44 +0000 |
|---|---|---|
| committer | Simon Marlow <marlowsd@gmail.com> | 2008-08-05 13:35:44 +0000 |
| commit | 1867a7bb8c59ea514b4f47f5434842543933ec9a (patch) | |
| tree | 4f622970ba88bf408e2884d0ea3819230abf1232 /docs/users_guide | |
| parent | ea9a5be67418ab76c4fa33736a3335b517c9e7f9 (diff) | |
| download | haskell-1867a7bb8c59ea514b4f47f5434842543933ec9a.tar.gz | |
Add -XPackageImports, new syntax for package-qualified imports
Now you can say
import "network" Network.Socket
and get Network.Socket from package "network", even if there are
multiple Network.Socket modules in scope from different packages
and/or the current package.
This is not really intended for general use, it's mainly so that we
can build backwards-compatible versions of packages, where we need to
be able to do
module GHC.Base (module New.GHC.Base) where
import "base" GHC.Base as New.GHC.Base
Diffstat (limited to 'docs/users_guide')
| -rw-r--r-- | docs/users_guide/flags.xml | 6 | ||||
| -rw-r--r-- | docs/users_guide/glasgow_exts.xml | 23 |
2 files changed, 29 insertions, 0 deletions
diff --git a/docs/users_guide/flags.xml b/docs/users_guide/flags.xml index ef57f13730..32eb56548c 100644 --- a/docs/users_guide/flags.xml +++ b/docs/users_guide/flags.xml @@ -959,6 +959,12 @@ <entry>dynamic</entry> <entry><option>-XNoFunctionalDependencies</option></entry> </row> + <row> + <entry><option>-XPackageImports</option></entry> + <entry>Enable <link linkend="package-imports">package-qualified imports</link>.</entry> + <entry>dynamic</entry> + <entry><option>-XNoPackageImports</option></entry> + </row> </tbody> </tgroup> </informaltable> diff --git a/docs/users_guide/glasgow_exts.xml b/docs/users_guide/glasgow_exts.xml index 63c5dbdf2e..14848159a4 100644 --- a/docs/users_guide/glasgow_exts.xml +++ b/docs/users_guide/glasgow_exts.xml @@ -1568,6 +1568,29 @@ necessary to enable them. </para> </sect2> +<sect2 id="package-imports"> + <title>Package-qualified imports</title> + + <para>With the <option>-XPackageImports</option> flag, GHC allows + import declarations to be qualified by the package name that the + module is intended to be imported from. For example:</para> + +<programlisting> +import "network" Network.Socket +</programlisting> + + <para>would import the module <literal>Network.Socket</literal> from + the package <literal>network</literal> (any version). This may + be used to disambiguate an import when the same module is + available from multiple packages, or is present in both the + current package being built and an external package.</para> + + <para>Note: you probably don't need to use this feature, it was + added mainly so that we can build backwards-compatible versions of + packages when APIs change. It can lead to fragile dependencies in + the common case: modules occasionally move from one package to + another, rendering any package-qualified imports broken.</para> +</sect2> </sect1> |