[cduce-users] default match policy not working in sequences

Alain Frisch Alain.Frisch at inria.fr
Thu Nov 4 01:47:36 CET 2004


Giuseppe Castagna wrote:
>> - reuse predefined types:
>>
>>    [ <a>_ /A | <b>_ /B ]   (where A and B are already defined)
>>
> 
> I do not see any advantage here. This is equivalent to
> 
> [ <a>_ A | <b>_ B ]

No, actually, it is equivalent to [ <a>_ | <b>_ ] (if A and B contain 
the empty sequence). Sorry, I really meant something like:

[ (<a>_ /A | <b>_ /B)  R ]

where R is a complex regexp.

> Yes this is an advantage. In any case I believe that / is not a good 
> syntax. Too close to difference, and field removal, and possible 
> confusion with projections. I know that we are running out of symbols 
> but we should pick a different one.

I did not invent the / notation; I took it from lex (the lexer 
generator), where it expresses a constraint on the trailing context.

Any other suggestion for the syntax ?

>> 3. it is the notation I use in my PhD manuscript (p 176 of
>>    the version you have)
>>
> 
> Come-on, every reader will have commited suicide before arriving at page 
> 176 (you may wonder why I am still alive) :-)

Gmrbl :-/


-- Alain



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