Create a system.
Takes a map with the following elements:
- A keyword to refer to this system later.
- Namespaced symbol of the system’s function. If
:process-fnis provided, :process can be omitted. However the system won’t be serializable in this case.
- System’s function itself.
:process-fnwill be resolved automatically if
- Components this system will read.
- Components this system will read and write.
Components not specified in either
:writes won’t be accessible to the system.