Nannying (was: Array comprehension syntax)
brendan at mozilla.com
Tue Sep 25 13:27:18 PDT 2012
Allen Wirfs-Brock wrote:
> I note that in your toy grammar you avoid the comma issue at the front and in the for clauses by using AssignmentExpression in those positions.
> The current ES6 spec. draft has AssignmentExpression at the front, and Expression in the for and if clauses. However, there is also a editor's note that suggests that AssignmentExpression should be considered for all three positions.
There's still no ambiguity if the toy grammar changes to
'[' AssExpList ']'
| '[' AssExp FOR ID OF Exp IF Exp ']'
| AssExpList ',' AssExp
| Exp ',' AssExp
| ID '=' AssExp
The "readability" concern would matter if people actually wrote
unparenthesized comma expressions in such comprehensions, but Nanny-me
says they won't, and Mary Poppins agrees.
Again, it's not our job to prevent people from writing something that
might confuse someone. JS has lots of room in its grammar for that. I
agree with Dave, in absence of evidence of real ambiguity or another
technical grammar problem.
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