import: Add Elm importer.

* guix/import/elm.scm, guix/scripts/import/elm.scm: New files.
* Makefile.am (MODULES): Add them.
* guix/scripts/import.scm (importers): Add "elm".
* doc/guix.texi (Invoking guix import): Document Elm importer.
* doc/contributing.texi (Elm Packages): Mention it.
* tests/elm.scm ("(guix import elm)"): New test group.

Signed-off-by: Ludovic Courtès <ludo@gnu.org>

1 files changed, 25 insertions, 0 deletions

diff --git a/doc/guix.texi b/doc/guix.texi
index 3eff660f0e..5a07c995b9 100644
--- a/doc/guix.texi
+++ b/doc/guix.texi
@@ -13157,6 +13157,31 @@ and generate package expressions for all those packages that are not yet
 in Guix.
 @end table
 
+@item elm
+@cindex elm
+Import metadata from the Elm package repository
+@uref{https://package.elm-lang.org, package.elm-lang.org}, as in this example:
+
+@example
+guix import elm elm-explorations/webgl
+@end example
+
+The Elm importer also allows you to specify a version string:
+
+@example
+guix import elm elm-explorations/webgl@@1.1.3
+@end example
+
+Additional options include:
+
+@table @code
+@item --recursive
+@itemx -r
+Traverse the dependency graph of the given upstream package recursively
+and generate package expressions for all those packages that are not yet
+in Guix.
+@end table
+
 @item opam
 @cindex OPAM
 @cindex OCaml