[parenscript-devel] four patches to PS-LOOP etc.

[Vladimir Sedach]

Hi Boris,

The generated code is much harder to read - there's a block declared
there that does nothing, and you have to figure out that it does
nothing if you're trying to read the code. It's deceptive.

I'd like to make a generalized solution involving only BLOCK itself,
so that other code that generates BLOCKs can take advantage.

Vladimir

On Sat, Jul 28, 2012 at 9:36 AM, Boris Smilga <boris.smilga at gmail.com> wrote:
> On 21 Jul 2012, at 14:01, Vladimir Sedach wrote:
>>
>> [...] Because patch 0003 causes all LOOPs to be
>>
>> wrapped in blocks, and loop is used in various places, this means that
>> this code:
>>
>> (defun hello-world (&key ((:my-name-key my-name) 1))
>>     my-name)
>>
>> Used to look like:
>>
>> function helloWorld() {
>>     var _js2 = arguments.length;
>>     for (var n1 = 0; n1 < _js2; n1 += 2) {
>>         switch (arguments[n1]) {
>>         case 'my-name-key':
>>             myName = arguments[n1 + 1];
>>         };
>>     };
>>     var myName = 'undefined' === typeof myName ? 1 : myName;
>>     return myName;
>> };
>>
>> And now looks like:
>>
>> function helloWorld() {
>>     nilBlock: {
>>         var _js2 = arguments.length;
>>         for (var n1 = 0; n1 < _js2; n1 += 2) {
>>             switch (arguments[n1]) {
>>             case 'my-name-key':
>>                 myName = arguments[n1 + 1];
>>             };
>>         };
>>     };
>>     var myName = 'undefined' === typeof myName ? 1 : myName;
>>     return myName;
>> };
>>
>> I need a bit of time to think about the right way to fix that
>> (probably by fixing block not to emit if the body contains no return,
>> since it is all lexical) [...]
>
>
> Another approach would be to introduce a special PS-LOOP keyword (called
> NOBLOCK or something in the same vein) which would make LOOP expand to PROGN
> rather than to BLOCK.  Then we could add the keyword to the internal LOOPs
> and get the PROGNs back.  This is simpler than checking for RETURNs, though
> not necessary more elegant.
>
> That said, I don't quite see from the example above why the issue needs
> fixing in the first place.  You can't really mean that the block introduces
> local scope for myName etc.? — JavaScript doesn't have block scope.  So what
> is your idea?
>
> Yours,
>  — B. Smilga.
>
>
>
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