[PATCH v4] packages: Support for full Guix specification

[Olivier Dion]

Guix package specifications match:

  PACKAGE [@VERSION] [:OUTPUT]

thus the following are all valid package specifications:

  - "guile"
  - "guile@3.0.8"
  - "guile:debug"
  - "guile@3.0.8:debug"

This is not currently supported by gwl.  To do so, simply mark the package with
its output through Guile's object properties infrastructure.

The `package-output' procedure can then be used to retrieve the package's 
output.
---
 gwl/packages.scm  | 24 +++++++++++++++++++-----
 gwl/processes.scm |  5 ++++-
 2 files changed, 23 insertions(+), 6 deletions(-)

diff --git a/gwl/packages.scm b/gwl/packages.scm
index 6fe82d4..23bc09d 100644
--- a/gwl/packages.scm
+++ b/gwl/packages.scm
@@ -31,18 +31,22 @@
                           inferior-package-version
                           inferior-package-native-inputs
                           inferior-package-derivation))
+  #:use-module ((guix ui)
+                #:select (package-specification->name+version+output))
   #:use-module (ice-9 format)
   #:use-module (ice-9 match)
   #:use-module (srfi srfi-1)
   #:use-module (srfi srfi-26)
   #:use-module (srfi srfi-34)
   #:use-module (srfi srfi-35)
+  #:use-module (srfi srfi-71)
   #:export (current-guix
             inferior-store
 
             lookup-package
             valid-package?
             package-name
+            package-output
 
             bash-minimal
             build-time-guix
@@ -73,11 +77,18 @@
 
 (define (lookup-package specification)
   (log-event 'guix (G_ "Looking up package `~a'~%") specification)
-  (match (lookup-inferior-packages (current-guix) specification)
-    ((first . rest) first)
-    (_ (raise (condition
-               (&gwl-package-error
-                (package-spec specification)))))))
+  (let ((name version output
+              (package-specification->name+version+output specification)))
+    (let* ((inferior-package
+            (lookup-inferior-packages (current-guix)
+                                      name version))
+           (package (match inferior-package
+                      ((first . rest) first)
+                      (_ (raise (condition
+                                 (&gwl-package-error
+                                  (package-spec specification))))))))
+      (set-object-property! package #:gwl/package-output output)
+      package)))
 
 (define (valid-package? val)
   (or (package? val)
@@ -100,6 +111,9 @@ the version.  By default, DELIMITER is \"@\"."
     ((? inferior-package? pkg)
      (inferior-package-full-name pkg))))
 
+(define (package-output pkg)
+  (object-property pkg #:gwl/package-output))
+
 (define bash-minimal
   (mlambda ()
     (lookup-package "bash-minimal")))
diff --git a/gwl/processes.scm b/gwl/processes.scm
index ce40d12..4fc4d6d 100644
--- a/gwl/processes.scm
+++ b/gwl/processes.scm
@@ -643,7 +643,10 @@ PROCESS."
   (let* ((name         (process-full-name process))
          (packages     (cons (bash-minimal)
                              (process-packages process)))
-         (manifest     (packages->manifest packages))
+         (manifest     (packages->manifest (map
+                                            (lambda (pkg)
+                                              (list pkg (package-output pkg)))
+                                            packages)))
          (profile      (profile (content manifest)))
          (search-paths (delete-duplicates
                         (map search-path-specification->sexp
-- 
2.36.0