The Eina library provides a number of data types and tools targeted at working with the remainder of the EFL framework although they can be used on their own. For example, Lists and Arrays can be used both to send collections of objects to a native function or get the result of a native function. Or someone can use just the logging facilities.
Logging API reference - The Logging framework allows setting up different log domains and levels.
Iterator functions API reference - Allows sequential item access to Eina containers using iterator functions.
Acessor functions API reference - Allows random item access to Eina containers using accessor functions.
Value wrapping API reference - Abstracts generic data storage and access.