On Apr 29, 2010, at 3:48 PM, Mark S. Miller wrote:
On Thu, Apr 29, 2010 at 3:32 PM, Brendan Eich <[email protected]>
wrote:As far as I can tell, this is covered by ECMA-262 7.9.2:
The source
a = b + c
(d + e).print()
is not transformed by automatic semicolon insertion, because the
parenthesised expression that begins the second
line can be interpreted as an argument list for a function call:
a = b + c(d + e).print()
Formally, that makes sense. But given that all the other
<keyword> ... "{" ... "}"
productions, if they occur at the beginning of a statement, end with
the "}", I think this reading of the let expression may be
confusing. What if we adopt the same (admittedly unpleasant) rule we
already have for the "function" keyword: It can't begin an
expression statement. If it occurs at the beginning of a statement,
it is a statement. If you want a let expression in that position,
surround it with parens.
Yeah, we can do this -- it will not break us since we do it for
function and { already. In particular, you can't start an object
initialiser at the front of a statement -- this bites destructuring
assignment with an object pattern too, but in practice it's ok:
majority case uses a binding keyword to destructure to fresh names;
minority case, you parenthesize.
Thanks for pointing this out.
/be
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