Simplify purge command

gitto/git.scm

@@ -38,6 +38,7 @@
             repo-name
             repository?
             repository-location<?
+            repository-location-exists?
             repository-name<?
             same-repository?))
 
@@ -65,6 +66,10 @@
   "Compary REPO1 and REPO2 to see if REPO1 should be considered less."
   (string<? (repo-location repo1) (repo-location repo2)))
 
+(define (repository-location-exists? repo)
+  "Check to see if REPO's location exists."
+  (file-exists? (repo-location repo)))
+
 (define (repository-name<? repo1 repo2)
   "Compare REPO1 and REPO2 to see if REPO1 should be considered less."
   (string<? (repo-name repo1) (repo-name repo2)))

gitto/main.scm

@@ -228,10 +228,7 @@ registered repository as absolute paths."
 
 Go through the list of registered repositories and remove all the ones
 which no longer point to a git repository."
-  (set! repositories
-        (filter (lambda (repo)
-                  (file-exists? (repo-location repo)))
-                repositories))
+  (set! repositories (filter repository-location-exists? repositories))
   (save-repositories-list))
 
 (define-command (remove repository)