Extending a generic varags proc

[shirleyquirk]

Not completely sure what you're asking, more detail or example ( pseudo) code 
would help but just in case I understand:

Yes, generic varargs are possible, and yes you can type specialise: 
    
    
    import sequtils
    proc trs[T](args:varargs[T]):seq[T] =
      when T is int:
        args.mapIt(it*2)
      else:
        args.toSeq()
    
    echo trs(3,4,5) # @[6,8,10]
    echo trs('a','b','c') #['a','b','c']
    
    
    Run