Linker

A linker is used to turn an AIR tree into a single PIL file. The linking process operates in the following way:

1. Create an empty PIL file
2. Start from the main AIR. If it defines a degree, let main_degree be that value. If it does not, let main_degree be 1024.
3. For each AIR
   1. Create a new namespace in the PIL file
   2. If a degree is defined, check that it equals main_degree and error out if it does not. If no degree is defined, set the degree to main_degree
   3. Add the constraints to the namespace
   4. Turn the links into lookups and add them to the namespace

The result is a monolithic AIR where:

• each machine instance is a namespace
• all namespaces have the same degree
• links between instances are encoded as lookup identities

More flexible approaches to the linking process will be explored in the future, such as allowing for machine instances of different degrees.