[erlang-questions] Integrating lager into our app

Roger Lipscombe <>
Thu Jan 21 16:12:00 CET 2016

You have to run the compiler with -pa ../lib/lager-2.0.3/ebin as well,
so that it knows where to find the parse transform.

On 21 January 2016 at 15:04, Martin Koroudjiev <> wrote:
> Hello,
> I am trying to include lager into our application but I am having
> problems. I include the lager ebin directory on startup with: -pa
> "../lib/lager-2.0.3/ebin"
> Then I start lager with: lager:start().
> I define a constant as: -define(dbg(Fmt), lager:debug(Fmt)).
> But when I try to use it in the code:
> ?dbg("Hello").
> it says: ** exception error: undefined function lager:debug/1
> I've checked lager's help page on github and saw that a parse_transform
> must be set to lager_transform. Why is this needed?
> And how to actually do it? I compile my source files with erlc and pass
> the transform option with +"{parse_transform, lager_transform}" but then
> the code doesn't compile because lager_transform module is not present
> at that time.
> Thank you,
> Martin
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