Not all programmers (engineer or otherwise) are guys -- probably worth keeping that in mind if you want this to be a welcoming community for everyone (:
I'm Canadian too. I sometimes use "you guys" when speaking to a group that has women in it; I don't use "guy" in the singular when talking about generic technical roles because it implies that being a guy is part of the job. In many cases this is effectively true due to sexism in the industry, so it's not something to take lightly.
I don't think this is what you intended, to be clear! But I do think that is how it would be interpreted, even by Canadian women.