Using QuickCheck for testing if a list is shuffled

Asked Mar 03 '20 at 06:46

Active Mar 03 '20 at 11:49

Viewed 106 times

I need to use QuickCheck to check if a list of integers is truly shuffled

prop_fastShuffle_correct :: [Int] -> Property
prop_fastShuffle_correct s = ???

My shuffle function has this signature:

fastShuffle :: [a] -> IO [a]

No need to go for full correctness of every potential property of your shuffle, e.g., that it’s pseudorandom.

Can someone point me into the right direction? I'm not too familiar with QuickCheck.

edited Mar 03 '20 at 11:49

lehins

asked Mar 03 '20 at 06:46

Tomer

1

See e.g. https://stackoverflow.com/q/46791466/126014 for a similar type of problem. – Mark Seemann Mar 03 '20 at 07:01
4

What is being truly shuffled? – Redu Mar 03 '20 at 07:08
3

Realistically, you can only check that it's a permutation of the input, which can be implemented using something like `sort output == sort input`. – chi Mar 03 '20 at 11:32
1

A shuffle function can sometimes return the function exactly in the same order as it was. – Willem Van Onsem Mar 03 '20 at 17:17

0 Answers0