W1: more robust definition of primes in tests

nubBy changed subtly for ghc 7.10 closes #15 closes #16
opqdonut · May 25, 2015 · bc32d75 · bc32d75
1 parent 844a4db
commit bc32d75
Showing 1 changed file with 3 additions and 1 deletion.
diff --git a/W1Test.hs b/W1Test.hs
@@ -170,7 +170,9 @@ ex16_pyramid =
   f (pyramid n) === ([0..n] ++ [n-1,n-2..0])
   where f xs = map read $ split ',' xs
 
-primes = nubBy (\x y -> mod x y == 0) [2..]
+primes = go [2..]
+  where go (x:xs) = x : go (filter (notDivBy x) xs)
+        notDivBy x y = mod y x /= 0
 
 ex17_smallestDivisor_prime = do
   forAll (elements $ take 12 primes) $ \p ->