Maude-help mailing list

[Juan Ignacio Perna <jiperna AT cs.york.ac.uk>]

Hello,

I am trying to implement a language of expressions (this is part of a 
bigger language) and I am interested in having list of both variable 
names and expressions.
My idea was to make a generic list module and then generate two 
instantiations of it. When trying to do that, I stumbled upon loads of 
error messages of the form:

Advisory: "filename.maude" line .... (fmod: ....): operator  ..... has 
been imported from both "filename.maude", line ..... (fmod ....) and 
"filename.maude", line .... (fmod: ....) with no common ancestor.

I think the problem is, somehow, that I have the Var as a subsort of Exp 
(the error does not arise if I instantiate one of the lists with the 
view Int instead of Exp, for example), but I don't fully understand why 
and how to solve it.

I am attaching a simplified version of the file for you to be able to 
reproduce the error. I am using core maude for windows (2.4)

Many thanks,

Juan
fmod SET{X :: TRIV} is 
  sort Set{X} .
  subsort X$Elt < Set{X} .
  
  ops empty : -> Set{X} .
endfm

fmod EXP is
  sorts Var Exp .
  subsorts Var < Exp .
endfm

view Var from TRIV to EXP is
   sort Elt to Var .
endv

view Exp from TRIV to EXP is
   sort Elt to Exp .
endv

fmod VAR-SET is
  protecting SET{Var} * (sort Set to SetVar) .
endfm 

fmod EXP-SET is
  protecting SET{Exp} * (sort Set to SetExp) .
endfm 

fmod EXPS is
  protecting EXP-SET .
  protecting VAR-SET .
endfm