Support arbitrary percision

[icyrockcom]

Right now it looks like it's hard-coded to 30. Would there be any downsides to adding a config function to set precision to some other number? Asking due to it potentially being wrong as it would make equality not work after changing the precision mid-program.

[sharkdp]

It would definitely be dangerous to change precision mid-program, yes. Apart from that, I don't see any objections. Maybe we could name the function appropriately (unsafeChangePrecision or similar) and write some documentation that it should only be used at the very beginning?

[icyrockcom]

unsafeChangePrecision (or maybe unsafeSetPrecision which is a bit shorter?) seems like a good idea to me. Would that be enough though? E.g. if someone did something along the lines of:

import Data.Decimal
import Effect.Console

decj = sqrt pi

main = do
  unsafeSetPrecision 100
  deck = sqrt pi
  logShow $ decj == deck

would log false, right? I guess that can be added to the documentation and may be enough - what do you think?

[sharkdp]

I think someone needs to try :-)