Initial data commit

Task/Amb/Python/amb-4.py

@@ -0,0 +1,79 @@
+from itertools import chain
+
+
+# amb :: [a] -> (a -> [b]) -> [b]
+def amb(xs):
+    return lambda f: list(
+        chain.from_iterable(
+            map(f, xs)
+        )
+    )
+
+
+# main :: IO ()
+def main():
+
+    xs = enumFromTo(1)(10)
+    print ('Pythagorean triples from integers 1-10:')
+    print (
+        amb(xs)(
+            lambda x: amb(xs)
+            (lambda y: amb(xs)
+                (lambda z: when(
+                    x * x + y * y == z * z
+                )(
+                    (x, y, z)
+                )
+            ))
+        )
+    )
+
+    # joins :: String -> String -> Bool
+    def joins(a, b):
+        return a[-1] == b[0]
+
+    print ('\nRC problem given above:')
+    print (
+        amb(['the', 'that', 'a'])(
+            lambda w1: amb(
+                ['frog', 'elephant', 'thing']
+            )(lambda w2: amb(
+                ['walked', 'treaded', 'grows']
+            )(lambda w3: amb(
+                ['slowly', 'quickly']
+            )(lambda w4: when(
+                joins(w1, w2) and joins(w2, w3) and joins(w3, w4)
+            )(
+                (w1, w2, w3, w4)
+            ))))
+        )
+    )
+    print('\nAdditional problem reference in procedural version above:')
+    print(
+        amb([1, 2, 3])
+        (
+            lambda x: amb([4, 5, 6])
+            (
+                lambda y: when(x * y != 8)
+                (
+                    (x, y)
+                )
+            )
+        )
+    )
+
+# GENERIC -------------------------------------------------
+
+
+# enumFromTo :: (Int, Int) -> [Int]
+def enumFromTo(m):
+    return lambda n: list(range(m, 1 + n))
+
+
+# when :: Bool -> [a] -> [a]
+def when(p):
+    return lambda x: [x] if p else []
+
+# MAIN ---
+if __name__ == '__main__':
+    main()