Perfect numbers: Difference between revisions

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@@ Line 2,325: / Line 2,325: @@
 Or, a little faster (by restricting the search space):
-<lang python>from operator import (add)
+<lang python>from functools import (reduce)
+from operator import (add)
 from math import (sqrt)
@@ Line 2,331: / Line 2,332: @@
 # main :: IO ()
 def main():
-    print(filter(perfect, xrange(1, 10000)))
+    print(
+        list(filter(perfect, enumFromTo(1)(10000)))
+    )
 # perfect :: Int - > Bool
 def perfect(n):
-    lows = filter(
+    lows = list(filter(
         lambda x: 0 == (n % x),
-        xrange(1, 1 + int(sqrt(n)))
+        enumFromTo(1)(int(sqrt(n)))
-    )
+    ))
     return (1 < n) and(
         n == sum(
@@ Line 2,355: / Line 2,358: @@
 # GENERIC --------------------------------
-# concatMap::(a - > [b]) - > [a] - > [b]
+# concatMap :: (a -> [b]) -> [a] -> [b]
 def concatMap(f):
-    return lambda xs: (
+    def go(xs):
-        reduce(add, map(f, xs), [])
+        a = []
+        for x in xs:
-    )
+            a = a + f(x)
+        return a
+    return lambda xs: go(xs)
+# enumFromTo :: Int -> Int -> [Int]
+def enumFromTo(m):
+    return lambda n: list(range(m, 1 + n))