Re: Typol Operator

[td@babar.inria.fr (Thierry Despeyroux)]

In article <18670@sophia.inria.fr>, kuehne@pi.informatik.th-darmstadt.de (Thomas Kuehne) writes:

|> I need an language operator exclusivly for semantic purposes.
|> It is irrelevant for the set of data that can be expressed with the language.
|> Therefore i do not want to include it in my METAL language definition.
|> 
|> I tried to introduce it with the "define" construct of TYPOL.
|> 
|> Unfortunatly it introduces a new PHYLUM (EVENT), that is differnt to my
|> aimed PHYLUM (MENU::EVENT). The "define" syntax does not allow to specify
|> the disambiguated PHYLUM (MENU::EVENT).
|> 
|> Is there a possiblity to extend my existing language with an operator 
|> without changing the original language definition.


There is no modular definition of languages in METAL. 
The "define" of Typol only allows you to define (small)
languages that use types from other languages, but not
to extend a phylum. 

However, I do not recommend to use "define" as there is
no corresponding centaur formalism.

So you will have to pollute your existing language or to
copy (a part of) it. If you look carefully at the Typol
definition, you will see that you can parse a complete
sequent (with schemes in it) in a judgement declaration,
and the error will only be detected at type-checking
only, just for this reason of lack of modularity.



Thierry
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