It's the 6-th test on 'concat' suite in final tests. List.repeat([1,2,3]).concat().take(4) Expected: [1, 2, 3, 1] This error and the description of concat method - "list must be a list of lists" made me think that repeat on arrays should return list of lists otherwise List.repeat([1,2,3]).concat() should throw an error.

Oh, thanks, I got it. My List has passed all sample tests but I am still struggling with infinite lists in the main tests. If you don't mind I have question about repeat function.
From the description "List.repeat(x) => an infinite list, every element of which is x" it was not abvious (for me) that List.repeat([1,2,3]) create a list of lists and not list of arrays. Should we treat every array as list ?

Hi, I have error message caused by test line Test.assertDeepEquals( List.empty.foldr( () => | , Math.E ), Math.E ); ReferenceError: _ is not defined