Initial data commit

Task/Cantor-set/Python/cantor-set-2.py

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+'''Cantor set – separating model from display'''
+
+from functools import (reduce)
+import itertools
+
+
+# cantor :: [(Bool, Int)] -> [(Bool, Int)]
+def cantor(xs):
+    '''A Cantor segmentation step.'''
+    def go(tpl):
+        (bln, n) = tpl
+        m = n // 3
+        return [
+            (True, m), (False, m), (True, m)
+        ] if bln and (1 < n) else [tpl]
+    return concatMap(go)(xs)
+
+
+# cantorLines :: Int -> String
+def cantorLines(n):
+    '''A text block display of n
+       Cantor-segmented lines.
+    '''
+    m = n - 1
+    repeat = itertools.repeat
+    return '\n'.join(
+        [showCantor(x) for x in (
+            reduce(
+                lambda a, f: a + [f(a[-1])],
+                repeat(cantor, m),
+                [[(True, 3 ** m)]]
+            )
+        )]
+    )
+
+
+# showCantor :: [(Bool, Int)] -> String
+def showCantor(xs):
+    '''A text block display of a list of
+       Cantor line segments.
+    '''
+    return ''.join(
+        concatMap(lambda tpl: tpl[1] * ('█' if tpl[0] else ' '))(
+            xs
+        )
+    )
+
+
+# main :: IO ()
+def main():
+    '''Testing to depth 5'''
+
+    print(
+        cantorLines(5)
+    )
+
+
+# GENERIC -------------------------------------------------------------
+
+# concatMap :: (a -> [b]) -> [a] -> [b]
+def concatMap(f):
+    '''A concatenated list over which a function has been mapped.
+       The list monad can be derived by using a function f which
+       wraps its output in a list,
+       (using an empty list to represent computational failure).'''
+    chain = itertools.chain
+    return lambda xs: list(
+        chain.from_iterable(map(f, xs))
+    )
+
+
+# MAIN ---
+if __name__ == '__main__':
+    main()