Some operations are impossible to program in Erlang itself, or are impossible to program efficiently. For example, there is no way to find out the internal structure of an atom, or the time of day, etc. – these lie outside the scope of the language. Erlang therefore has a number of built-in functions (BIFs) which perform these operations.
For example atom_to_list/1 converts an atom to a list of (ASCII) integers which represents the atom and date/0 returns the current date:
> atom_to_list(abc).
[97,98,99]
> date()
{93,1,10}A full list of all BIFs is given in Appendix.