How to set a plex order in Maple with the number of variables to be determined by input?

I want to write a function to give the Groebner basis respect to lex order of two input polynomials, but the numbers of variables are given by the input, not known a priori. To be precise, I start with:

GBoftwo:=proc(f,g,Var)

where Var is a list of variables, for example the the input can be GBoftwo(x^2+y,x+z^2,[x,y,z]). Then the entire code could be:

GBoftwo:=proc(f,g,Var)
with(Groebner);
local F, n;
F:=[f,g];
n:=nops(Var);
retern Basis(F,plex(Var[1],...,Var[n]))
end proc;

Then the error massage says: Error, unable to parse.

How can I overcome this problem?

Thanks!

I didn't figure it out by any method, I don't know if it's the defect of the Basis command.

Solution

You got the error message because you misspelled return as retern. So you have a syntax error.

You cannot properly utilize with inside a procedure.

You should uneval-quote the global name plex, since it's not a protected name and could be assigned some value at the top-level.

You don't need n, since op(Var) provides the expression sequence of the elements of the list Var.

restart;

GBoftwo:=proc(f,g,Var::list(name))
  uses Groebner;
  local F:=[f,g];
  return Basis(F,':-plex'(op(Var)))
end proc:

GBoftwo(x^2+y,x+z^2,[x,y,z])

      [ 4       2    ]
      [z  + y, z  + x]

GBoftwo(x^2+y,x+z^2,[y,x,z])

      [ 2       4    ]
      [z  + x, z  + y]

note: Yout example procedure is quite simple, and can be further simplified to just a single line (at which point it's hardly a time-saver; you could as easily just call Basis directly). Hence I suppose that you are practicing/learning, and that this is just a programming experiment.

restart;
GBoftwo:=proc(f,g,Var::list(name))
  Groebner:-Basis([f,g],':-plex'(op(Var)))
end proc:

GBoftwo(x^2+y,x+z^2,[x,y,z])

        [ 4       2    ]
        [z  + y, z  + x]

with(Groebner):

# and now, just a few characters longer...
Basis([x^2+y,x+z^2],plex(x,y,z))

         [ 4       2    ]
         [z  + y, z  + x]