tris-fusion

Tp9/tri-fusion/merge_sort.py

@@ -122,7 +122,18 @@ def is_sorted(l: ApLst, comp: Callable[[T, T], int]=compare) -> bool:
     $$$ is_sorted(native_to_list([1, 2, 4, 3]))
     False
     """
-    ...
+    if l.is_empty():
+        return True
+    else:
+        if l.tail().is_empty():
+            return True
+        else:
+            
+            if comp(l.head(), l.tail().head())>0:
+                
+                return False
+            else:
+                return is_sorted(l.tail(), comp)
 
 
 def split(l: ApLst) -> tuple[ApLst, ApLst]:
@@ -141,8 +152,7 @@ def split(l: ApLst) -> tuple[ApLst, ApLst]:
     $$$ all(k in l for k in l3)
     True
     """
-    ...
-
+   
 
 def merge(l1: ApLst, l2: ApLst,
           comp: Callable[[T, T], int]=compare) -> ApLst:
@@ -156,8 +166,7 @@ def merge(l1: ApLst, l2: ApLst,
     $$$ list_to_native(merge(native_to_list([1, 3, 4, 9]), native_to_list([1, 2, 5])))
     [1, 1, 2, 3, 4, 5, 9]
     """
-    ...
-
+   
 
 def mergesort(l: ApLst, comp: Callable[[T, T], int]=compare) -> ApLst:
     """