Use MathJax format for complexity annotations

[konsumlamm]

I did the following changes, via search & replace:

• /O(1)/ -> \(O(1)\)
• /O(n)/ -> \(O(n)\)
• /O(m+n)/ -> \(O(m+n)\)
• /O(min(m,n))/ -> \(O(\min(m,n))\)
• /O(m+min(n1,n2))/ -> \(O(m+\min(n_1,n_2))\)

Additionally i formatted complexities that previously had no formatting and some manual changes (see the second commit).

[konsumlamm]

@lehins @Shimuuar what do you think?

[lehins]

@konsumlamm Just by itself it doesn't look too much different from before this PR, however if you can do this search and replace to \(\mathcal{O}(...)\) instead, which is the way it is done in Data.List, that would be awesome! What do you think?

[konsumlamm]

Sure, I can do that.

[Bodigrim]

It's perfectly valid and much more common to use O instead of \mathcal{O}, which is a very recent innovation. All classic books from Knuth to Okasaki use an old plain O and I do not really see a good reason to diverge.

[lehins]

It's perfectly valid and much more common

This new big O typesetting is already used in base haddock, and if we add this to vector it'll make it pretty common in Haskell ecosystem.

which is a very recent innovation

Nothing is wrong with using innovations

All classic books from Knuth to Okasaki use an old plain O and I do not really see a good reason to diverge.

I see a reason. It looks pretty!

So @Bodigrim, we have a perfectly valid PR that I like and you don't, what do we do now? @Shimuuar any input?

[Shimuuar]

Personally I would use plain O. Easier to type, easier to read in source. But I don't really have opinion about this. Either way is fine

[lehins]

Fair enough. Sorry @konsumlamm, despite that I am all for this cute big O, we live in a democracy with the other two maintainers, and both of them expressed preference in favor of the plain O. If you'll able to persuade them, you have my vote, but for now I have to close this PR.