[functional-tests] Tests are now identified by a list of symbols.

Improved formatting too.

functional-tests/list-utils.scm

@@ -1,7 +1,15 @@
 (library
   (list-utils)
-  (export tails intersperse iterate accumulate)
-  (import (rnrs))
+
+  (export tails
+          intersperse
+          iterate
+          comparing
+          list-group-by
+          accumulate)
+
+  (import (rnrs)
+          (srfi s8 receive))
 
   (define (tails xs)
     (if (null? xs)
@@ -22,6 +30,19 @@
         '()
         (cons (fn) (loop (- count 1))))))
 
+  (define (comparing cmp key)
+    (lambda (x y)
+      (cmp (key x) (key y))))
+
+  ;; Assumes the list is already sorted
+  (define (list-group-by pred xs)
+    (if (null? xs)
+        '()
+        (let ((fst (car xs)))
+         (receive (g1 gs) (partition (lambda (x) (pred fst x)) (cdr xs))
+                  (cons (cons fst g1)
+                        (list-group-by pred gs))))))
+
   ;; calculates a running total for a list.  Returns a list.
   (define (accumulate xs)
     (let loop ((xs xs) (total 0))