Feature/lenses

[tmrdlt]

I added lenses to our project.
For the yesod models they can be added automatically by adding mpsGenerateLenses = True in Model.hs.
For the other models they have to be generated manually.
After adding lenses, fields of records can be read and manipulated using this syntax:

gameStateEntity ^. gameStateEntityStatus             -- returns "Ongoing"
gameStateEntity & gameStateEntityStatus .~ "Ongoing" -- sets Status to "Ongoing". Can be used to update multiple fields aswell. Just add more & 
gameStateEntity & gameStateEntityBombCount +~ 1      -- increments hasBomb field by 1

See also:
https://riptutorial.com/haskell/example/2987/lenses-for-records
Updating multiple fields trick:
https://mail.haskell.org/pipermail/haskell-cafe/2013-November/111288.html

I didn't use the lenses syntax for all the yesod template files as I think we are going to remove them soon anyways.

[ndrsllwngr]

Thank you for the explanation @timunkulus. Nice work!

[tmrdlt]

@griase94 wenn checkst wie man hier und weiter unten die Lense Syntax anwendet, gerne anpassen ;)

[griase94]

I think we can simplyfy the revealing and flagging syntax quite a lot by using https://hackage.haskell.org/package/matrix-lens, I will give it a try after implementing the mutable state with TVars

[ndrsllwngr]

I think we can simplyfy the revealing ans flagging syntax quite a lot by using https://hackage.haskell.org/package/matrix-lens

Sounds good! Nice find.