Update to purescript 0.12.0

[revazi]

Currently I'm reading the book and working with examples, but for them to work I had to install previous version of the language. If you're not already working on example code update for the latest version I'm willing to contribute.

[vyorkin]

I see that Justin Woo has already started the work here #135.
I want to help too. As I can see there are only two chapters left (related to purescript-react): 8 and 10.
I can't mention him here for some reason, let's ask him in FP slack?

[vyorkin]

@revazi Just had a chat with Justin - he doesn't mind if we try to help with the remaining 2 chapters. So I'll start with chapter 8 and make a PR to his branch https://github.com/justinwoo/purescript-book/tree/0.12-psc-package.
PR for chapter 8: https://github.com/justinwoo/purescript-book/pull/1/files

[revazi]

@vyorkin Thanks for the info. I'm currently reading book and doing exercises with previous version. Upon finishing the book(in a few days) I'll ping you and let you know how I'll be able to contribute.

[AesaKamar]

Most of my confusion was with the references to purescript-eff.
As I understand now, purescript 0.12 uses purescript-effect?

[vyorkin]

@AesaKamar yeah, this was a major breaking change (at least most noticeable), but in most cases it's as trivial as just replacing the Eff (foo :: FOO, bar :: BAR | eff) a with Effect a

[vyorkin]

Also, the book itself needs to be updated along with the examples (after upgrading examples I suppose)