Probably a platform issue, and it was probably transient.

Issue not reproducible in 2020. Closing.

Fixed.

I would argue against doing so as it promotes boolean blindness. Also, nowhere in the domain of the problem does it contain an operation in which two directions are tested for equality.

Python 3 should be enabled.

The initial state of the haskell solution is wrong. The function signature should be [[Double]] -> Double and not [[Int]] -> Double

For Haskell, I am getting "Missing language" when submitting my answer.

No random tests in Haskell.

The description should mention that the result should be rounded to 1 decimal place in C.

Making this function safe should not be done via returning a string. Instead a sum type like Maybe or Either should be used. It seems the original Haskell solution used Either, but I guess it was removed.

I would have preferred catMaybes and partition to be moved into the list section because at the point you reach them you do not yet know how lists are going to work. Also the functions are over lists anyways, so it's that weird to put them with the other list functions. I do like the current order of Maybe to Either to List though.