quoted atoms in type specs

Ryan Zezeski <>
Tue Sep 28 04:05:31 CEST 2010

Is there a reason to use a quoted atom rather than a bare atom in a type
specification.  E.g., in the reference manual is the following example:

Atom :: atom()
    | Erlang_Atom %% 'foo', 'bar', ...

I also notice this in a the module getopt in the rebar source code.

-type arg_type() :: 'atom' | 'binary' | 'boolean' | 'float' | 'integer' |

Why are the atoms being quoted? I was able to compile a module where the
type specification uses bare atoms. Why not declare it that way?


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