Beta/One: Mutable/Lockable INTEGER! semantics

[hostilefork]

A goal of Beta/One is not to teach things in the tutorial that will need to be unlearned. The necessity of having a story for the handling of "BigNum" arithmetic suggests that the INTEGER! type should have BigNum range...which raises the issue for efficiency of the use of non-immediate values.

The concept is outlined here in a forum post:

https://forum.rebol.info/t/planning-ahead-for-bignum-arithmetic/623

Support for BigNum arithmetic is likely not a realistic goal to occur for Beta/One...as it involves too much rewiring of the arithmetic code--as well as decisions on whether to use the existing bigint.c for Crypto from axTLS or not.

However, the approach described in the post of using non-immediate values is viable, and could be used to give the semantics required for efficient bignums--just within the range of today's 64-bit integers. This means that:

x: copy 10
add x 5
print x

Would print out 15. The proposal outlines that this would be the behavior of ADD but not of +, which would not modify its argument, and return an immutable number...which could be implemented efficiently without the use of a memory allocation.

This lesser goal is a requirement to implement in time for Beta/One.