Not until you pointed it out. What I am looking for is somthing that
will return true for:
DirectedGraph(String)
FunctionGraph(String)
DirectedGraph(NNI)
FunctionGraph(DoubleFloat)
DirectedGraph(DirectedGraph(String))
... and so on
that is any domain of the form
x(y)
where x is an instance of FiniteGraph
and y is an instance of SetCategory
Well, look at your definition. You have
FiniteGraph(S): Category == Definition where
S: SetCategory
https://github.com/hemmecke/fricas-svn/blob/master/src/algebra/graph.spad.pamphlet#L842
and
DirectedGraph(S): Exports == Implementation where
S: SetCategory
...
Exports ==> FiniteGraph(S) with
...
https://github.com/hemmecke/fricas-svn/blob/master/src/algebra/graph.spad.pamphlet#L1807
The y has to be of type SetCategory in any case. I the compiler accepts
something that is not of type SetCategory when x=FiniteGraph or
x=DirectedGraph, then that's a bug in the compiler.
What you basically want is to ignore what the argument type is. I've no
idea whether that is appropriate, but since you want it...
You could create a dummy category that simply encodes the fact that the
domain is "a FiniteGraph over something". You can do this in the
following way.
Similar to this...
https://github.com/hemmecke/fricas-svn/blob/master/src/algebra/attribs.spad.pamphlet
FiniteGraphCategory: Category == with ()
FiniteGraph(S: SetCategory): Category == Join(FiniteGraphCategory, ...)
And... you guessed it ... you then ask
if X has FiniteGraphCategory then ...
Well, of course you can cheat, i.e. give the FiniteGraphCategory to a
domain that does not really inherit from FiniteGraph(S). You have to
follow a convention and discipline.
I hope that helps for this particular case. The general case is
unfortunately impossible.
Ralf
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