2011/3/29 Mike Samuel <[email protected]>: > 2011/3/29 Bob Nystrom <[email protected]>: >> Wouldn't => work the same way? >> (a, b) => >> It parses "(a, b)" thinking it's a grouped comma operator (not exactly a >> common expression FWIW), then it hits "=>" realizes it's a function >> parameter decl, and then either backtracks or just transforms the left-hand >> AST into a param decl. > > An AST won't cut it. You have to use a parse tree because there are > valid grouped comma operators containing only identifier operands that > are not valid parameter lists, e.g. ((a), b) > > Once you do have a way to make the necessary distinctions, => is just > another right associative operator that you need to pick a precedence > for.
The fact that there are parameter lists that are not valid grouped comma operators, () and (a), shouldn't cause problems. And there shouldn't be any subtle semicolon insertion bugs. bar = foo () => 4 will reliably produce a syntax error when the parameter list is stolen by a callable expression on a previous line. _______________________________________________ es-discuss mailing list [email protected] https://mail.mozilla.org/listinfo/es-discuss
