2 Diving In

2.2 Atoms and Strings

2.2.1 Atoms

Atoms are a data type in Erlang that is used to represent non-numerical constants. In LFE, the typographical limitations of Erlang don't apply, since they're always quoted in LFE ;-)

Atoms have a value: the same as their text:

> 'strag
strag
>

We saw this in the section on Boolean operators with the atoms of true and false. Since there are no Boolean types in Erlang or LFE, the atoms true and false are used instead.

Here are some more examples of atoms:

> 'Vogon
Vogon
> '_Gargle_Blaster
_Gargle_Blaster
> '+
+
> '*
*
> '|and now with hyperspace bypasses|
|and now with hyperspace bypasses|
>

Though very simple, atoms have a huge impact on our everyday use of Erlang and LFE, primarily in the area of pattern matching. Hold that thought, though; we're not quite ready for it yet!

Furthermore, atoms are stored differently in Erlang than strings. They take up less space and are more efficient to compare than strings.

2.2.2 Strings

Now we come to the oddball of Erlang: the string. In truth, there is no such thing. Strings in Erlang are just lists of integers:

> '"Don't Panic."
"Don't Panic."
> (list 68 111 110 39 116 32 80 97 110 105 99 46)
"Don't Panic."
>

Because Erlang (and thus LFE) strings consume 8 bytes per character on 32-bit systems and 16 bytes on 64-bit systems, they are not very efficient. As such, if you need to work with long strings in LFE, you probably want to use (binary ...), but that's in the next section :-)