Thanks, it worked

Try selecting version 8.2, if available.

    FoldingThroughAFixedPointSpec.hs:1:53:
    Not in scope: `main'
    Perhaps you meant `min' (imported from Prelude)

Anyone else seeing this when submitting?

It's a problem with the runner, this solution worked at some point but now it doesn't. Check the posts in Discourse, you're not the only one with that problem.

I tried your solution, it reports
"STDERR
Execution Timed Out (12000 ms)"

I tested this under a very small data range because my own solution is quite slow.

T_T

There doesn't seem to be performance tests in this Kata so chances are your "proof" is relying on a circular argument, e.g. a * b = b * a because b * a = a * b because a * b = b * a because ...

If you've checked your proof extensively and found no such arguments, then my best advice is to see where you could perhaps shorten your proof by using fewer steps (easier said than done, I know). Hope this helps :)

Any hint what to do when timing out?

After looking at it a bit deeper it's the same thing over again:

if v is ommited, fill the array with undefined

The error is actually

`prefill': wrong number of arguments (given 1, expected 2) (ArgumentError)
	from `<main>'`

Yes, I know it's not the perfect place to put such a test, and Ruby's testing framework still has that bug, but clearly you haven't read the descriptions or read the previous issues where I've answered the exact same thing. So...

Note that I have passed all other tests, another user seems to have the same problem as I had.

This has been checked. My program only accepts integers or integer-formatted strings.

•if n is anything other than an integer or integer-formatted string (e.g. '123') that is >=0, throw a TypeError

There are strings as inputs. Make sure you handle them properly.

(Also, the test does work when it's 0, so you're probably failing at other test cases.)

Ruby testcase: n = 0 gives me error all the time, can any time have a look?

Done