When programmers see a type union expression for the first time, and are going to intuitively understand "|" to be an operator, which has a new meaning when applied to types. Programmers routinely use parens around complex expressions that involve multiple operators, for readability and to ensure they didn't make a mistake around operator precedence. But parens are never required in those places, and it would add an odd asymmetry to the language to require them here.
I vote they are dropped unless there is a compelling technical reason, related to machine parsing. Peter On Fri, Mar 21, 2008 at 10:46 PM, Waldemar Horwat <[EMAIL PROTECTED]> wrote: > There is no solid technical reason for requiring parentheses here. They're > here because of people's preferences. I don't find them particularly useful > here. > > Waldemar > > > > > Peter Hall wrote: > > Now that union type uses "|" instead of "," for the delimiter, could > > the parentheses be made optional? It seems like parentheses are used > > elsewhere only for grouping and function calls/definitions. > > > > UnionType ::= Type ( "|" UnionType )? > > > > which should be easily distinguishable from a bitwise OR expression. > _______________________________________________ Es4-discuss mailing list [email protected] https://mail.mozilla.org/listinfo/es4-discuss
