restrictions on let declarations

Rick Waldron waldron.rick at gmail.com
Thu Jan 30 09:29:44 PST 2014


On Thu, Jan 30, 2014 at 12:24 PM, Brendan Eich <brendan at mozilla.com> wrote:

> Rick Waldron wrote:
>
>>
>>     It is -- special forms that have heads can bind in bodies. We see
>>     this with formal parameters to functions, also with the defunct
>>     let blocks and let expressions of ES4. ML has similar forms.
>>
>>     We made this block scoping, and how! Turns out Dart did the same.
>>     Each iteration gets a fresh binding. If there's a closure in the
>>     first part of the for(;;) head that captures the loop variable, it
>>     gets a "0th iteration" binding.
>>
>>
>> Also, there was very positive interest in Waldemar's proposed if-scoped
>> let, here: https://mail.mozilla.org/pipermail/es-discuss/2013-
>> December/035077.html
>>
>
> Nick Krempel  proposed that upthread, just for the record.
>

Yes, my mistake--I had looked in December archives and found what I thought
was the OP. This is the correct OP from November:

https://mail.mozilla.org/pipermail/es-discuss/2013-November/035060.html


Rick


>
> Yeah, it's good. It comes from C++ but goes back to Algol, IIRC. Another
> precedent for block-scoped bindings that are declared in heads.
>
> /be
>
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