gexp: Add symlink-to procedure.

* guix/gexp.scm (symlink-to): New procedure.
* doc/guix.texi (G-Expressions): Document it.

Change-Id: I7c1ba3a29a4e5350cb4f196185b7171c4750b6b8
Signed-off-by: Maxim Cournoyer <maxim.cournoyer@gmail.com>

2 files changed, 16 insertions, 0 deletions

diff --git a/doc/guix.texi b/doc/guix.texi
index ef8504bb3e..02f472246a 100644
--- a/doc/guix.texi
+++ b/doc/guix.texi
@@ -12692,6 +12692,17 @@ file.  Here's an example:
 This yields an @code{etc} directory containing these two files.
 @end deffn
 
+@deffn {Procedure} symlink-to target
+Return a @code{<computed-file>} that is a symbolic link to target.
+Note, that the target does not need to exist at the build time.  One of
+uses is to put arbitrary symlinks into user's home:
+
+@lisp
+(service home-files-service-type
+  `(("Sync" ,(symlink-to "/storage/Sync"))))
+@end lisp
+@end deffn
+
 @deffn {Procedure} directory-union name things
 Return a directory that is the union of @var{things}, where @var{things} is a list of
 file-like objects denoting directories.  For example:
diff --git a/guix/gexp.scm b/guix/gexp.scm
index 302a1bb553..cf94d9d5f4 100644
--- a/guix/gexp.scm
+++ b/guix/gexp.scm
@@ -119,6 +119,7 @@
             file-union
             directory-union
             references-file
+            symlink-to
 
             imported-files
             imported-modules
@@ -2182,6 +2183,10 @@ or dangling symlink ~a" target source)))
               files)))))
    #:guile guile))
 
+(define (symlink-to target)
+  "Return an object that is a symlink to TARGET."
+  (computed-file "link" (gexp (symlink (ungexp target) (ungexp output)))))
+
 (define* (directory-union name things
                           #:key (copy? #f) (quiet? #f)
                           (resolve-collision 'resolve-collision/default))