townengine/docs/interop.md

# interoperability
api needs to facilitate easy interoperability with other languages and tools,
for that certain considerations are taken:

* number of public api calls is kept at the minimum
* procedure parameters can only use basic types, no aggregates, with exception of Vec/Matrix types and alike,
  with no expectation on new additions (see [/include/twn_types.h](../include/twn_types.h))
* optionals can be expressed via pointer passage of value primitives, assumed immutable, with the NULL expressing default
* no opaque types, only keys
* when mutation on input is done, - it shouldn't be achieved from a mutable pointer, but the return value
* return value could be a simple aggregate that is translatable to pure data dictionary
* module prefix is used for namespacing, actual symbols come after the prefix (`<module>_<symbol>`)
* symbols should not contain numerics at the start nor after the namespace prefix
* 32 bit floating point is the only numeric type
* [/include/twn_api.json](../include/twn_api.json) file is hand-kept with a schema to aid automatic binding generation and tooling