`Value` type should be math-safe

[sinitcin]

The current type Value represents just wrapper around u128. We should make a type that handles overflows and underflows properly to avoid situations when we accidentally might create a vulnerability.

[altonen]

I believe there was some discussions on this topic already somewhere? I think it's worth linking here if someone remembers where that discussion took place.

[sinitcin]

I believe there was some discussions on this topic already somewhere? I think it's worth linking here if someone remembers where that discussion took place.

@iljakuklic as far as I remember you have prepared something that was related to this issue?

[iljakuklic]

I believe there was some discussions on this topic already somewhere? I think it's worth linking here if someone remembers where that discussion took place.

@iljakuklic as far as I remember you have prepared something that was related to this issue?

I posted a very rough design sketch here #67 (comment). I also stumbled upon a trait in Substrate [1] that uses Rust's affine types to make sure you do not accidentally inflate token supply. Arithmetic operations "consume" the values so you can't use them multiple times. Not sure how exactly it is used, just noticed that the other day.

[1] https://paritytech.github.io/substrate/monthly-2021-09+1/frame_support/traits/tokens/imbalance/trait.Imbalance.html