HaloO, Xavier Noria wrote:

IMO to include something related to infinity you need to stick with some particular model and forget the rest.

Well spoken. But I think that the model John has chosen is a bit too restrictive. If a type has a notion of Zero it could have a similar notion of infinity just at "the other side". For the Int type in a two's complement mindset that means that counting through the Ints in increasing order from zero is the same as going in the *same* direction from -Inf where Zero is the unreachable infinity. Here I assume that both Zero and -Inf are represented as the infinite string of 0 binary digits. One is little endian the other big endian, though. If you don't know where you are in your infinite sequence of 0 then Zero is indistinguishable from -Inf and -1 is indistinguishable from +Inf, both are infinite sequences of 1. E.g. +('9' x Inf) == -1 could be a true comparison that doesn't even scratch the memory resources of temporary hardware. With the above in mind we could e.g. also define ^-4 === -4..-1 most conveniently as (*-4)..(*-1) for array indexing from the back in forward order. Or perhaps that is ^(*-4) and the ^-4 is for indexing in front of the array. The Whatever type is also behaving a bit like Inf because it represents different numbers in different arrays. That is my Whatever of Int $idx = -4; always indexes arrays from the back but behaves like normal -4 when no special handling is required, IOW it sets the shift to zero. Note that infix:<op>:(Whatever[::X],X-->Whatever[X]) but infix:<op>:(::X, Whatever[X]-->X) are sort of non-commutative. Note that the default value for Whatever is Inf ;) Regards, TSa. -- "The unavoidable price of reliability is simplicity" -- C.A.R. Hoare "Simplicity does not precede complexity, but follows it." -- A.J. Perlis 1 + 2 + 3 + 4 + ... = -1/12 -- Srinivasa Ramanujan