>From 1ea5eaae4b492c82358c7394c22cd46497388449 Mon Sep 17 00:00:00 2001
From: Roel Janssen <address@hidden>
Date: Sun, 28 Aug 2016 00:54:06 +0200
Subject: [PATCH] guix package: Display generation diffs.

---
 guix/scripts/package.scm |  2 +-
 guix/ui.scm              | 34 ++++++++++++++++++++++++++++++++++
 2 files changed, 35 insertions(+), 1 deletion(-)

diff --git a/guix/scripts/package.scm b/guix/scripts/package.scm
index 2a751a4..32cbcdc 100644
--- a/guix/scripts/package.scm
+++ b/guix/scripts/package.scm
@@ -640,7 +640,7 @@ processed, #f otherwise."
        (define (list-generation number)
          (unless (zero? number)
            (display-generation profile number)
-           (display-profile-content profile number)
+           (display-profile-content-diff profile number)
            (newline)))
 
        (cond ((not (file-exists? profile))      ; XXX: race condition
diff --git a/guix/ui.scm b/guix/ui.scm
index 906b349..cb056a0 100644
--- a/guix/ui.scm
+++ b/guix/ui.scm
@@ -87,6 +87,7 @@
             matching-generations
             display-generation
             display-profile-content
+            display-profile-content-diff
             roll-back*
             switch-to-generation*
             delete-generation*
@@ -1070,6 +1071,39 @@ DURATION-RELATION with the current time."
           (format #t (_ "~a\t(current)~%") header)
           (format #t "~a~%" header)))))
 
+(define (display-profile-content-diff profile number)
+  "Display the changed packages in PROFILE with generation specified by NUMBER."
+
+  (define (equal-entry? first second)
+    (string= (manifest-entry-item first)
+             (manifest-entry-item second)))
+
+  (define* (display-entries entries #:optional (prefix " "))
+    (for-each
+     (match-lambda
+       (($ <manifest-entry> name version output location _)
+        (format #t "  ~a ~a\t~a\t~a\t~a~%"
+                prefix name version output location)))
+     entries))
+  
+  (define (display-profile-content-diff-between profile older newer)
+    (if (= older 0)
+        (display-profile-content profile newer)
+        (let* ((old (profile-manifest (generation-file-name profile older)))
+               (new (profile-manifest (generation-file-name profile newer)))
+               (installed (lset-difference equal-entry?
+                                           (manifest-entries new)
+                                           (manifest-entries old)))
+               (removed (lset-difference equal-entry?
+                                         (manifest-entries old)
+                                         (manifest-entries new))))
+
+          (display-entries installed "+")
+          (display-entries removed "-"))))
+
+  (let ((previous (previous-generation-number profile number)))
+    (display-profile-content-diff-between profile previous number)))
+
 (define (display-profile-content profile number)
   "Display the packages in PROFILE, generation NUMBER, in a human-readable
 way."
-- 
2.9.3