On 2016-06-02 15:52, Erik Bray wrote:
1. If flipper makes heavy use of bitwise negation then to prevent errors should explicitly cast values to a type where ~x means bitwise negation and not reciprocal (or anything else) in the first place.
No because it's not only in the Flipper program itself, it's also in their user interface.
But it's not just Flipper: ~x is an important difference between Sage Integers and Python ints. Ideally, Integer and int should be compatible as much as possible.
2. I know this is probably anathema to mathematicians, but couldn't "1/" be viewed as a two character unary operator meaning reciprocal? :)
Sort of, but keep in mind efficiency. Often, taking the reciprocal is more efficient than coercion followed by a general division.
Second, there might be structures where reciprocal makes sense but not division in general. I cannot immediately think of something, but it might exist.
3. Even if you managed to get / added as a unary operator in Python wouldn't you still have to support ~ for reciprocal for the foreseeable future if Sage is already using it that way?
I'm sure that every other problem is trivial compared to getting Python accept this :-)
Anyway, you can use the preparser plus deprecations to deal with that.
4. Before going through the hazard that is adding new syntax to Python, would this be easier to implement just in the Sage interpreter as syntactic sugar instead?
No, because we really want this in Python code, not just the Sage command line. Currently, ~x is used a lot in the Sage library.
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