Stephen Wilson wrote: > "Bill Page" <[EMAIL PROTECTED]> writes: > > > On 08 Jul 2007 15:21:52 -0400, Stephen Wilson wrote: > > > If so, I have a strategy to make such Unions usable (but it may be a > > > while before I find the time to implement it). If not, then there is > > > an easy fix to assert the uniformity of Union branches. > > > > > > > I think mixed union constructions should be consider syntax errors. > > I personally agree as well. Unfortunately, the current Spad parser > is, well, difficult to change. I can check the uniformity of Union > branches at a post-parsing stage to at least get the assertion into > the system. Perhaps in time my new parser could be used as a full > replacement for the current one. >
A little nitpick: if mixed union constructions are considered errors for me it is clearly a semantic error. I think it is better to catch such errors on a post-parsing stage. Why this may matter: syntax errors frequently leave parser in a confused state, making hard to detect other errors. Also for users is seem easier to have simple syntax + set of semantic constraints than to encode constraints in syntax. -- Waldek Hebisch [EMAIL PROTECTED] _______________________________________________ Axiom-developer mailing list Axiom-developer@nongnu.org http://lists.nongnu.org/mailman/listinfo/axiom-developer