hyperthunk/proper — comment on commit 7e7dada3aeeb3221c0caf48105d73cf794f67abd
File:  line 0
By hyperthunk:

Ho Kostis,

You are absolutely write about the type spec being incorrect. Furthermore, I suspect the declaration should really be `{module(), function_name()}` as the callback must behave like `io:format/2` in order to be compatible with the current `on_output` implementation, and therefore *must* have arity 2. I will also add some test cases!

My primary use case is to be able to provide the `on_output` option through `rebar.config` which isn't able to hold a fun reference as it [rebar] uses `file:consult/2` to read its config. For example:

```erlang
{qc_opts, [
long_result,
{on_output, {quickcheck_reports, write_report, []}}
]}.
```