Re: To get things started...

At 01:50 PM 11/22/00 -0500, Chaim Frenkel wrote:
> >>>>> "DS" == Dan Sugalski <[email protected]> writes:
>
>DS> At 07:36 AM 11/21/00 -0500, David Grove wrote:
> >> However, one thing is seriously lacking in this theory... if the parser is
> >> perl, how does the perl parse? (Sort of a woodchuck chucking wood type of
> >> thing.) Somehow, the external parser API thingy has to know enough perl
> >> (through the chosen language) to be able to handle the parsing.
>
>DS> Nope. We do it in two phases. The end result will not actually parse perl
>DS> code to build the parser (we'll provide bytecode for that) but to 
>start we
>DS> can run the parser through perl 5 to get a syntax tree until the perl 6
>DS> engine's capable of doing it itself.
>
>Sounds fragile.
>
>We bootstrap on perl5 to get a bytecode stream, and then that bytecode
>stream had better stay supported.

Yup. It's one way to ensure backwards compatibility... :)

>I remember this game. The Symbolics Lisp Machine (and probably other's of
>this ilk) did the same. You were able to modify the World to do anything
>and hopefully you saved the original so that when your world fell down
>around your ears, you had somewhere to get back to.
>
>Please tell me that I'm wrong. (And that this will be able to parse code
>at acceptable speed.)

You're not wrong, but I don't think this is a huge problem. Lots of systems 
do it like this at the moment--GCC comes to mind as a first one, but there 
are lots of others. Granted it does mean that we'll need to ship a 
bytecode-compiled version of the parser as part of the perl distribution, 
but that's not a big deal. (Besides, that's what Larry wants, and he's got 
a point)

It's also possible we'll do the parser mainly in C with perl hooks, but 
that's not the direction I've been pointed in.

>Anyway, what does this have to do with the API?

Well, the choice of language for the parser's relevant, but other than that 
it's really more of a generic -internals thing.

					Dan

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Dan Sugalski                          even samurai
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