[aisleriot] api: Add helper to shuffle the cards on a slot

[Christian Persch <chpe src gnome org>]

commit 69bc35719cc006d2314484f29bb485fb93df0f13
Author: Christian Persch <chpe src gnome org>
Date:   Thu Oct 10 21:28:22 2019 +0200

    api: Add helper to shuffle the cards on a slot
    
    https://gitlab.gnome.org/GNOME/aisleriot/issues/6

 games/api.scm | 16 +++++++++++-----
 1 file changed, 11 insertions(+), 5 deletions(-)
---
diff --git a/games/api.scm b/games/api.scm
index 7ecf75d6..309c1371 100644
--- a/games/api.scm
+++ b/games/api.scm
@@ -143,14 +143,20 @@
       (cons (make-card value suit) 
            (make-deck-list-ace-high init-value (+ 1 value) suit))))
  
-
+; shuffle the card list
+(define (shuffle-card-list card-list)
+  (let* ((vec (list->vector card-list))
+        (len (vector-length vec)))
+    (shuffle-deck-helper vec '() 0 len)))
 
 ; shuffle the card list in DECK
 (define-public (shuffle-deck)
-  (let* ((vec (list->vector DECK))
-        (len (vector-length vec)))
-    (set! DECK (shuffle-deck-helper vec '() 0 len))))
-                                            
+  (set! DECK (shuffle-card-list DECK)))
+
+; shuffle the card list in slot
+(define-public (shuffle-slot slot-id)
+  (set-cards! slot-id (shuffle-card-list (get-cards slot-id))))
+
 ; The playing area is divided into slots, where cards can be placed.
 ; Each slot can hold any amount of cards.  The slots are identified 
 ; using numbers assigned in order of their creation. The deck of cards