Importing Several Elements at a Time

Let , be distinct variables. Abbreviate

import  
     import  
          
     endimport
endimport

import ,  
     
endimport

In a similar way, define abbreviations

import , ..., 
     
endimport

Abbreviate

import , ..., 
     U() := true
     .
     .
     .
     U() := true
     
endimport

extend U with , ..., 
     
endextend

Later (in 5.4) we'll see how to import a number of elements that is not bounded a priori by any constant. Here is an example of the extend rule:

extend Nodes with ,  
   FirstChild(CurrentNode) := 
   SecondChild(CurrentNode) := 
   NextSib() :=  
endextend