[developers] type addenda and :< in TDL
Ann.Copestake at cl.cam.ac.uk
Thu Nov 27 23:42:20 CET 2008
So shall we agree that if there are no objections by Dec 5th, :< can
become identical in behaviour in type definitions to := ? I suggest
that if we do add a warning message, that we output only one message
on a grammar load.
> hi again,
> > from my perspective, it's there for backward compatability, but I'm
> > not keen to get rid of it since it'll cause hassle for no good reason.
> i just had a quick look at the relevant code in the LKB and PET. if we
> agree the `:=' vs `:<' distinction has no formal status in the DELPH-IN
> formalism, we can just treat `:<' as a syntactic variant. this will be
> trivial to implement and not show any effect on existing grammars. we
> could optionally issue a deprecation warning when `:<' is used, or just
> internally suggest to DELPH-IN grammarians that they avoid `:<'.
> > Presumably you will be changing some :< cases to :=, but I don't want
> > to force everyone to change all of them. You might be able to produce
> > a patch to tdltypeinput.lsp so it doesn't complain if you try and
> > augment a :< type, but that shouldn't be checked in, I feel.
> in fact, the current LKB allows type addenda on types defined by `:<',
> so there is a mild inconsistency here. PET enforces what i believe was
> the original TDL intention of `:<', viz. a sub-type definition without
> a local constraint (it can still inherit features and constraints). i
> would like the two systems to behave alike, but to decide what is right
> we would have to ascribe a formal interpretation to `:<', which i think
> we all agree is undesirable.
> i would be happy making the change reading `:<' as `:=' in both worlds.
> i would prefer seing `:<' deprecated. in my teaching experience, it is
> a potential source of confusion. would anyone object to that move?
> cheers - oe
> +++ Universitetet i Oslo (IFI); Boks 1080 Blindern; 0316 Oslo; (+47) 2284 0125
> +++ CSLI Stanford; Ventura Hall; Stanford, CA 94305; (+1 650) 723 0515
> +++ --- oe at ifi.uio.no; oe at csli.stanford.edu; stephan at oepen.net ---
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