September Morn Update

Task/Substring-Top-and-tail/Python/substring-top-and-tail-2.py

@@ -0,0 +1,55 @@
+from functools import (reduce)
+
+
+def main():
+    for xs in transpose(
+        (chunksOf(3)(
+            ap([tail, init, compose(init)(tail)])(
+                ['knights', 'socks', 'brooms']
+            )
+        ))
+    ):
+        print(xs)
+
+
+# GENERIC -------------------------------------------------
+
+# tail :: [a] -> [a]
+def tail(xs):
+    return xs[1:]
+
+
+# init::[a] - > [a]
+def init(xs):
+    return xs[:-1]
+
+
+# ap (<*>) :: [(a -> b)] -> [a] -> [b]
+def ap(fs):
+    return lambda xs: reduce(
+        lambda a, f: a + reduce(
+            lambda a, x: a + [f(x)], xs, []
+        ), fs, []
+    )
+
+
+# chunksOf :: Int -> [a] -> [[a]]
+def chunksOf(n):
+    return lambda xs: reduce(
+        lambda a, i: a + [xs[i:n + i]],
+        range(0, len(xs), n), []
+    ) if 0 < n else []
+
+
+# compose (<<<) :: (b -> c) -> (a -> b) -> a -> c
+def compose(g):
+    return lambda f: lambda x: g(f(x))
+
+
+# transpose :: [[a]] -> [[a]]
+def transpose(xs):
+    return list(map(list, zip(*xs)))
+
+
+if __name__ == '__main__':
+    main()