u2

u2/list_ops.py

@@ -0,0 +1,77 @@
+def append(list1, list2):
+    result = []
+
+    for element in list1:
+        result.append(element)
+
+    for element in list2:
+        result.append(element)
+
+    return result
+
+
+def concat(lists):
+    result = []
+
+    for current_list in lists:
+        for element in current_list:
+            result.append(element)
+
+    return result
+
+
+def filter(function, seq):
+    result = []
+
+    for element in seq:
+        if function(element):
+            result.append(element)
+
+    return result
+
+
+def length(seq):
+    count = 0
+
+    for element in seq:
+        count += 1
+
+    return count
+
+
+def map(function, seq):
+    result = []
+
+    for element in seq:
+        result.append(function(element))
+
+    return result
+
+
+def foldl(function, seq, acc):
+    for element in seq:
+        acc = function(acc, element)
+
+    return acc
+
+
+def foldr(function, seq, acc):
+    index = length(seq) - 1
+
+    while index >= 0:
+        acc = function(acc, seq[index])
+        index -= 1
+
+    return acc
+
+
+def reverse(seq):
+    result = []
+
+    index = length(seq) - 1
+
+    while index >= 0:
+        result.append(seq[index])
+        index -= 1
+
+    return result