is_sorted

TP9/tri-fusion/merge_sort.py

@@ -123,8 +123,9 @@ def is_sorted(l: ApLst, comp: Callable[[T, T], int]=compare) -> bool:
     $$$ is_sorted(native_to_list([1, 2, 4, 3]))
     False
     """
-    ...
-
+    while length(l)>1 and comp(l.head(),(l.tail()).head())<1:
+        l=l.tail()
+    return length(l)==1
 
 def split(l: ApLst) -> tuple[ApLst, ApLst]:
     """