does web page as one long string affect SEO ?

i have application that reproduce web pages out of templates
the output is one long html string without line breaks
my question is does it effect some how the SEO aspect ?

I'd have to see it specifically, but if you're talking about your HTML source having no whitespace, technically that shouldn't matter. I could see it tripping a spam filter if perhaps the software you use is notorious for spammers, but other than that, no technical issue to crawling or SEO.

As Chris said, it probably won't affect it any. However, it will make the code harder to read.