On Mon, Oct 27, 2014 at 10:32 AM, Nils Bruin <nbr...@sfu.ca> wrote: > On Monday, October 27, 2014 5:03:00 AM UTC-7, Volker Braun wrote: >> >> On the command line we could bind == to _isomorphic_, but use _identical_ >> in library code. Then we would have intuitive comparison and could still >> work with associative containers. >> > > I don't think this would be easy to do with the current preparser. Since > "==" is an infix operator, you need to fully parse the expression to > substitute the called operation reliably. Our current preparser only does > regex. It is of course entirely feasible to rewrite the REPL to first use > python's parser to give us an AST and do substitutions on that prior to > fully compiling and executing the statements. > > Furthermore, I think it is a strength of computer algebra systems such as > sage, magma, maple that their interface language is also used for large > parts of their libraries. This already doesn't quite hold true for sage, > but apart from "1/2" and "2^3" it's confined to syntax that produces errors > in straight python. I suspect that changing the semantics of "==" between > interface and library will be much more subtle and hence more problematic > (because casual testing may well not find differences). >
+1 > I see where your desire for "different parents means not equal" comes from > (I don't think we have to go all the way to is_identical: for p-adic > elements just insisting that precision also agrees should be sufficient), > but I don't quite see a way to implement it that won't lead to bigger > problems elsewhere. > I think this would be too constraining, even in library code. Either that or we'd have to make a bunch of exceptions (e.g. comparison to the int and Integer 1 and 0, ...) -- You received this message because you are subscribed to the Google Groups "sage-devel" group. To unsubscribe from this group and stop receiving emails from it, send an email to sage-devel+unsubscr...@googlegroups.com. To post to this group, send email to sage-devel@googlegroups.com. Visit this group at http://groups.google.com/group/sage-devel. For more options, visit https://groups.google.com/d/optout.
