On May 29, 2011, at 7:17 AM, Jose Antonio Perez wrote:
> 2011/5/29 Dmitry A. Soshnikov <dmitry.soshni...@gmail.com>
>
> That's it, exactly. We always looking for a shorter sugar. Though, the main
> thing that the sugar shouldn't be cryptic at the same time. Probably Erlang's
> list comprehensions are cryptic for someone, but again, taking into account
> arrow-functions, seems arrow-comprehensions aren't so cryptic.
>
> I think that your proposal based in Haskell's syntax is natural,clear and
> easy for the user. A EBNF grammar for it:
>
> ListComprehension : '[' Expression '|' IterableOrFilter
> (,IterableOrFilter)+ ']'
> IterableOrFilter: Id '<-' ArrayOrGenerator | BooleanFilter
>
> The problem is the LL(1) conflict with Array Literal, but that doesn't matter
> much, right? ;)
No, it's a big incompatibility that could result in no early error, rather a
shift in meaning.
We're not doing those without a really good reason. We don't have one here.
People seem to forget that | is an operator in the language. In
http://wiki.ecmascript.org/doku.php?id=strawman:block_lambda_revival I worked
around the lesser problem of parameter default values by requiring any default
value using bitwise-or to be parenthesized:
blam = {|x = (y | z)| x*x};
But block-lambdas do not use [] where | may be an operator in a single element
initialiser expression, so there's no further incompatibility.
Not so with square brackets.
Array comprehensions using for-in or the replacement (paren-free, probably
"for-of") Harmony syntax are in for ES.next.
/be_______________________________________________
es-discuss mailing list
es-discuss@mozilla.org
https://mail.mozilla.org/listinfo/es-discuss
