Update

021.fut

@@ -1,6 +1,8 @@
-def divsum(n: i32) = if n == 1 then 1 else
-    reduce (+) 0 (map(\x -> if n % x == 0 then x else 0) (1...(n / 2)))
+def divsum(n: i32) = if n == 1 then 1 
+    else (1...(n / 2)) |> map (\x -> if n % x == 0 then x else 0) |> i32.sum
 
 def amicable(n: i32) = if divsum(n) != n && divsum(divsum(n)) == n then n else 0
 
-def main = reduce (+) 0 (map(\x -> amicable(x)) (1...10000))
+def euler021(limit: i32) = (1...limit) |> map amicable |> i32.sum
+
+def main = euler021 10000