The type of a cartesian structure

This is not your typical category theory monoidal thing, as we store a recursive structure

The Interface type describes the Arity of the cartesian system structure

Put one structure before another

The structures will be dependent and must match in the interface

Note the order of arguments are flipped to support this syntax:

a |> before b

This will put a 'first'

Put two structures aside each other

The structures will be independent

Note the order of arguments are flipped to support this syntax:

a |> aside b

This will put a 'first'

Initialize a simple 1->1 arity morphism with label 'a'

Initialize a morphism with a given interface and label

The unit value

This is possibly not needed, but we'll start off using it.

This may disappear later.

Group a structure

This may be used to group substructures

Extract the outermost interface of the structure

Wrap a part of the structure with a label a