Cheeky

I have the same solution, but I kind of guessed it would work and have no idea why.

Could anyone explain the maths behind this solution? (If you do, please don't forget the spoiler flag)

too slow

yeah same here

why I cant find fractions module when using pycharm

I did the same thing and it timed out.

kysya!

muur!

Thx for your input, I had fixed both of them.
Alas, unMaybe, unEither used to be purely explanational (just write down why the given perfect code work, or why unEither is impossible, in the comment). However more than half of the people just completely ignore it. I guess some people just like internet points more than learning stuff.

Looks like the last func (the one about a ^ 1 = a) isn't tested at all. Was able to leave it as error "..." and still pass the tests. Of course, one can't tests if it is done the proper 'hard way', but the general functionality is testable nontheless.

We might also want to make it more apparent from the comments, that 'the hard way' stands for chain of operations on isomorphisms, just like the previous two examples. Judging by the existing solutions, half the folk just ignore the instructions completely. If not 'the hard way', the kata would be so much more boring and less insightful.

Note, that this pass2 fails on constant expressions more than 2 levels deep.

(pass1 "[]1+2+3+4") `shouldPass2` (Imm 10)

expected: Imm 10
        but got: Add (Imm 6) (Imm 4)