From 6980511b7391e65a307689f90e4ef5c1979e4541 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ludovic=20Court=C3=A8s?= <ludo@gnu.org>
Date: Thu, 28 Jul 2016 18:50:43 +0200
Subject: [PATCH] packages: Add 'hidden-package'.

* guix/packages.scm (hidden-package, hidden-package?): New procedures.
* gnu/packages.scm (fold-packages): Filter out 'hidden-package?'.
* tests/packages.scm ("hidden-package"): New test.
---
 gnu/packages.scm   |  3 ++-
 guix/packages.scm  | 15 +++++++++++++++
 tests/packages.scm |  4 ++++
 3 files changed, 21 insertions(+), 1 deletion(-)

diff --git a/gnu/packages.scm b/gnu/packages.scm
index 9496a270eb..68a9eef2ad 100644
--- a/gnu/packages.scm
+++ b/gnu/packages.scm
@@ -200,7 +200,8 @@ same package twice."
    (fold2 (lambda (module result seen)
             (fold2 (lambda (var result seen)
                      (if (and (package? var)
-                              (not (vhash-assq var seen)))
+                              (not (vhash-assq var seen))
+                              (not (hidden-package? var)))
                          (values (proc var result)
                                  (vhash-consq var #t seen))
                          (values result seen)))
diff --git a/guix/packages.scm b/guix/packages.scm
index bfb4c557ab..3646b9ba13 100644
--- a/guix/packages.scm
+++ b/guix/packages.scm
@@ -81,6 +81,8 @@
             package-maintainers
             package-properties
             package-location
+            hidden-package
+            hidden-package?
             package-field-location
 
             package-direct-sources
@@ -290,6 +292,19 @@ name of its URI."
                                                        package)
                                                       16)))))
 
+(define (hidden-package p)
+  "Return a \"hidden\" version of P--i.e., one that 'fold-packages' and thus,
+user interfaces, ignores."
+  (package
+    (inherit p)
+    (properties `((hidden? . #t)
+                  ,@(package-properties p)))))
+
+(define (hidden-package? p)
+  "Return true if P is \"hidden\"--i.e., must not be visible to user
+interfaces."
+  (assoc-ref (package-properties p) 'hidden?))
+
 (define (package-field-location package field)
   "Return the source code location of the definition of FIELD for PACKAGE, or
 #f if it could not be determined."
diff --git a/tests/packages.scm b/tests/packages.scm
index fc75e38730..7c9ad05c21 100644
--- a/tests/packages.scm
+++ b/tests/packages.scm
@@ -79,6 +79,10 @@
                     (write
                      (dummy-package "foo" (location #f)))))))
 
+(test-assert "hidden-package"
+  (and (hidden-package? (hidden-package (dummy-package "foo")))
+       (not (hidden-package? (dummy-package "foo")))))
+
 (test-assert "package-field-location"
   (let ()
     (define (goto port line column)