On Sat, May 21, 2011 at 12:37 PM, Brendan Eich <[email protected]> wrote:
> For http://wiki.ecmascript.org/doku.php?id=strawman:block_lambda_revival I
> have written up the Ruby-inspired {|x| x * x} syntax.
>
> Alternatives (ignoring keyword issues) that look more like function syntax
> (Peter's suggestion of lambda (x) { x * x }, e.g.) seem worse in this light:
> block lambdas do follow the correspondence principle, which is novel to JS
> with its C statements for control effects heritage.
>
> In this light, the use of | | to bracket formal parameters seems better than
> anything using (...) {...}. This is not an overriding concern, but it seems
> worth mentioning. We want block-lambdas or any such TCP-pure new thing to
> have syntax that says "look! something new here".
I don't think this idea of needing different syntax for different
semantics is a strong point in favour of the {||} syntax. ECMAScript
programmers are already accustomed to the keyword(){} syntax template
and have *no* trouble understanding the difference between the
following two bits of code and what return means in each.
if(a){return a;}
function(a){return a;}
> And, since the strawman builds on block syntax, we want the new form to have
> syntax that "looks like a block", in which you'd expect TCP purity for break,
> continue, return, |this|, and arguments.
Lambdas are useful for more than just blocks in control structures. I
don't think that use should be the sole force behind choosing the
syntax.
Peter
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