Programming Erlang, 2nd Edition

Term Comparisons

There are eight possible term comparison operations, shown in Table 6, ​Term comparisons​.

For the purposes of comparison, a total ordering is defined over all terms. This is defined so that the following is true:

number < atom < reference < fun < port < pid < tuple (and record) < map < list < binary

This means that, for example, a number (any number) is defined to be smaller than an atom (any atom), that a tuple is greater than an atom, and so on. (Note that for the purposes of ordering, ports and PIDs are included in this list. We’ll talk about these later.)

Having a total order over all terms means we can sort lists of any type and build efficient data access routines based on the sort order of the keys.

All the ...