[squeak-dev] Ometa vs XTreams PEG as Squeak core (was Re: Ometa)

Frank Shearar frank.shearar at angband.za.org
Wed Mar 30 19:37:32 UTC 2011

Michael Lucas-Smith presented XTreams last December at the UKSTUG 
meeting. If memory serves me correctly, his biggest complaint about 
OMeta was the mingling of semantic actions with the grammar.

I pointed out though that you can easily get around that by having your 
semantic actions indirected. http://www.angband.za.org/~frank/Pythia/ 
has a hopefully not too rubbish example of what I mean. It's written in 
OMeta 1, so don't expect it to work with OMeta 2!


On 2011/03/30 20:14, Casey Ransberger wrote:
> There's also Lukas' PetitParser. I've used it, and it's nice too. One thing it has over (and under) OMeta is that it's plain old Smalltalk (so no additional tool support is required) but OTOH I think OMeta's grammars are more terse and nicer to read. Mostly the same tech though (PEGs.)
> On Mar 30, 2011, at 11:26 AM, merlyn at stonehenge.com (Randal L. Schwartz) wrote:
>>>>>>> "Nikolay" == Nikolay Suslov<nsuslovi at gmail.com>  writes:
>> Nikolay>  First, making OMeta as the default preloaded package in
>> Nikolay>  Squeak. Then, review, redefine the parts in Squeak where patten
>> Nikolay>  matching and parsing is needed, reimplementing them using
>> Nikolay>  OMeta. Adopting existed programmer's tools for easily using of
>> Nikolay>  OMeta language, while working with source code (transcription,
>> Nikolay>  annotation, localisation, etc). Exploring, how "Undo" operation
>> Nikolay>  could be implemented in current Squeak using Worlds. And more..
>> While I'm very impressed with OMeta across multiple platforms, I think
>> putting it directly into Squeak as an always-handy parser might be a bit
>> premature.
>> I'd like a fair comparison with the PEG stuff of XTreams before I would
>> put my weight behind either proposal.  I say that because I'm inclined
>> to move Squeak towards Xtreams first, and if a PEG parser comes along
>> for free with that, we're already further than we've been in the past.
>> And the PEG Parser of XTreams doesn't require extraordinary browser
>> support, as OMeta does.
>> --
>> Randal L. Schwartz - Stonehenge Consulting Services, Inc. - +1 503 777 0095
>> <merlyn at stonehenge.com>  <URL:http://www.stonehenge.com/merlyn/>
>> Smalltalk/Perl/Unix consulting, Technical writing, Comedy, etc. etc.
>> See http://methodsandmessages.posterous.com/ for Smalltalk discussion

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