That's tested in the actual tests.

Yet valid monad implementation must comply with three laws which Haskell type system isn't able to check.

Also, in Haskell, type checking and being able to compile is usually good enough as "example tests".

Suggestion

Er, sorry, I didn't intend to mark my post as an Issue, seems it was done automatically by the feedback form.

I don't see how a Num instance would improve the Kata.

The examples do not necessarily show Haskell code, my intention was to convey a bit of the theory through some code. Additionally it makes the Show instance easier to define, to focus on what's really important about this Kata.

I don't think this is an issue, but thanks for your feedback anyway!

(.+.) and (.*.) are somewhat clumsy, would it be more natural to make polynoms a Num instance?
Also I think the "show" method for polynoms should output "x" rather than "x^1", because that's more convenient and is shown in all examples except for one.

There should be some example tests, of course.

There is another issue posted 11 months ago. Seems nobody gives a care :(

Ok. I'll have to rethink my solution then. Thanks for the tip.

Yes, you are right!

Good! I can't say about ES2015... Try to avoid sorting.

Fixed tests. JavaScript. I figured out why.

Now I just need a better solution to limit the length of [u] because it times out on the 'submit' tests.

Does using ES2015 slow the executuion?

Fixed tests or random tests please and which language?