On Thu, 10 Jan 2008, Ralf Hemmecke wrote: | | > | Suppose I test with students : | > | star (x, y) == x + y - x*y | > | | > | Then I prefer the command (x *%* y) *%* z to star (star (x, y), z)... | > | > If you use domains, you can overload + and *. | | Sometimes I also wish to be able to introduce new operators. | Unfortunately, they are fixed in SPAD as well as in Aldor. | | If I am allowed to dream then I would like to be able to write something | like | | (x: A) \oplus (y: A): A == ... | | (with \oplus being the actual (unicode) character for that operator). | | Of course that raises lots of questions and I am not 100% sure whether | it would be a good idea to | | 1) allow unicode in identifiers | 2) being able as a user to introduce new infix/postfix operators with | assigned precedences
What follows is a personal opinion, not logical universal statement. My personal experience with introducing new operator is largely negative (Haskell). Allowing user to introduce new operators can be seen as a god thing. It usually comes with allowing users to specify operator precendence (otherwise the feature is almost useless). In many cases, I got unpleasant surprises by combining third party modules each with its own idea by precedence of same operators. This is harder to detect than conflicting types. This isn't argument that it should not be allowed in Spad; just that I really don't have a need for it, and probably would not use it in my own codes. But, I realize that is not a universal opinion. To answer your questions: In general Spad would need to support unicode, not just because of user-defined operators. Yes, user defined infix, postfix and precedence should be allowed otherwise the feature becomes almost useless. But again, looking at the codes (mostly Haskell, ML) that make heavy use of it, I do not get the sense that codes get improved in clarity. -- Gaby ------------------------------------------------------------------------- Check out the new SourceForge.net Marketplace. It's the best place to buy or sell services for just about anything Open Source. http://ad.doubleclick.net/clk;164216239;13503038;w?http://sf.net/marketplace _______________________________________________ open-axiom-devel mailing list open-axiom-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/open-axiom-devel
