Maude-help mailing list

[Francisco Durán <duran AT lcc.uma.es>]

Hi Paolo,

>From the Maude book, probably it is in the manual as well:

Advisory. In fact, the symbol Universal does not denote a real sort: it is
instead a place holder for parsing purposes that is given an interpretation 
by the
polymorphic attribute (see Section 4.4.4). The concrete effect of the 
interpretation
of Universal is the instantiation in each connected component of the 
operators with
one or more Universal arguments.

What you need is probably a parameterized module. 

Cheers,

Paco

El 12/03/2011, a las 14:27, Paolo Picci escribió:

> hi all
> how i can use Universal type?
> Universal is not a real type i can't declare sometings like X:Universal .
> 
> fmod HET-LIST is
>  protecting CONVERSION .
>  sort List .
>  op nil : -> List .
>  op __ : Universal List -> List [ctor poly (1)] .
> endfm
> 
> this is an example from the book of maude.
> now how can use this list in the common use?
> how i can write a common function like head or tail over this
> function?
> i need a function like find for type String so:
> 
> op find : String List -> Bool .
> eq find(X:String, nil) = false .
> eq find(X:String, X:String XSHL:List) = true .
> 
> but the recursive case i cant write
> eq find(X:String,  X1:String XSHL:List) = find(X:String,
> XSHL:List)  .
> 
> because for example the list    1 2.2 "foo" 'qid "bar"  don't match
> the 3 eq
> 
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