The eval function

The eval function exposed by std:internals might not be available in all implementations. To prevent usage, the Hades Preprocessor exposes a variable (HAS_EVAL). The eval function returns whatever is returned by the content or null.

The std:internals library

The std:internals library contains miscellaneous functions for reflection. Like the eval function, it also has a preprocessor variable (HAS_INTERNALS) to determine weather or not you can use it. Some implementations might implement the std:internals library but not eval and vice-versa.