Modulo lens

[AlexKnauth]

Something like:

> (lens-view (modulo-lens 10) 16)
6
> (lens-set (modulo-lens 10) 16 9)
19

[jackfirth]

Ou, that's neat

[jackfirth]

Seems like something that should go in a library of math-specific lenses

[AlexKnauth]

I was thinking something like lens/data/number, in the lens-data package. (Edit: that would be where this would go if/when it's moved out of unstable)