Simplify list-repository-locations

Simplify `list-repository-location' by extracting the lambda's used and
defining them as separate procedures.

gitto/git.scm

@@ -37,6 +37,7 @@
             repo-location
             repo-name
             repository?
+            repository<?
             same-repository?))
 
 (define show-unchanged-branches? #f)
@@ -59,6 +60,10 @@
 (define (repository? repo)
   (is-a? repo <repository>))
 
+(define (repository<? repo1 repo2)
+  "Compary REPO1 and REPO2 to see if REPO1 should be considered smaller."
+  (string<? (repo-location repo1) (repo-location repo2)))
+
 (define-method (branch-pullable (branch <branch>))
   (force (slot-ref branch 'pullable)))
 

gitto/main.scm

@@ -43,13 +43,12 @@
 
 (define (list-repository-locations)
   "List the registered locations of repositories."
-  (for-each
-   (lambda (repo)
+  (for-each print-repository-location (sort repositories repository<?)))
+
+(define (print-repository-location repo)
+  "Print the location of REPO."
   (display (repo-location repo))
   (newline))
-   (sort repositories
-         (lambda (s1 s2)
-           (string<? (repo-location s1) (repo-location s2))))))
 
 (define (registered? repo)
   "Check if REPO has been registered."