1 files changed, 32 insertions, 1 deletions
diff --git a/bubble/bubble-sort.scm b/bubble/bubble-sort.scm
index 6efa819..fccaa4d 100644
--- a/bubble/bubble-sort.scm
+++ b/bubble/bubble-sort.scm
@@ -1,4 +1,35 @@
 (define-module (bubble-sort))
 
 (define-public (bubble-sort lst)
-  '())
+  (vector->list (bubble-sort-helper (list->vector lst))))
+
+(define (bubble-sort-helper vect)
+  "Recursively performs a bubble sort on VECT,
+stopping only when no elements were swapped."
+  (let ((vect-old (vector-copy vect)))
+    (try-swap-all vect)
+    (if (equal? vect-old vect)
+        vect
+        (bubble-sort-helper vect))))
+
+(define (try-swap-all vect)
+  "Performs a single iteration of the bubble sort
+algorithm on VECT."
+  (do ((i 0 (1+ i)))
+      ((> i (- (vector-length vect) 2)))
+    (try-swap vect i (1+ i))))
+
+(define (try-swap vect i j)
+  "Given two indices in ascending order, swap the
+indices in VECT if the element at i is greater than
+the element at j."
+  (cond
+   ((> i j) (error "Bad arguments passed to try-swap: i > j"))
+   ((> (vector-ref vect i) (vector-ref vect j)) (swap! vect i j))
+   (else vect)))
+
+(define (swap! vect i j)
+  "Swap the ith and jth elements in VECT."
+  (let ((tmp (vector-ref vect i)))
+    (vector-set! vect i (vector-ref vect j))
+    (vector-set! vect j tmp)))