Add operations on refined typed

Would be great to have a subset of the same operations available on unconstrained typed also available on refined types but tracking properties across operations. Even a small subset would probably already be a big win. I am thinking things like:

scala> val a: Int Refined Greater[W.`5`.T] = 10
scala> a + 1
res0: Int Refined Greater[W.`6`.T]

Are there any operations like this already? If not, adding a few to open the door for contributions in the same style might be a good way to get started.

[fthomas]

With the addition of “companions” for predefined refined types there is now a suitable place for operations with these types. For example, I experimented with addition of NonNegInts here: https://github.com/fthomas/refined/blob/76d812c3508e45e6413914dd76a81908ae5cf1db/modules/core/shared/src/main/scala/eu/timepit/refined/types/numeric.scala#L19-L28 Which preserve the non-negative property even in case of overflows:

scala> NonNegInt.MaxValue
res1: eu.timepit.refined.types.all.NonNegInt = 2147483647

scala> NonNegInt.plus(NonNegInt.MaxValue, NonNegInt(1))
res2: eu.timepit.refined.types.all.NonNegInt = 0

scala> NonNegInt.plus(NonNegInt.MaxValue, NonNegInt(2))
res3: eu.timepit.refined.types.all.NonNegInt = 1

[dwijnand]

eg.

scala> Int.MaxValue
res0: Int = 2147483647

scala> Int.MaxValue + 1
res1: Int = -2147483648