I've seen many studies that show that learning a second language (let's say French as a second and English as a first language for example) helps you to learn other languages in future. But would someone who can speak both French and English learn C++ faster? Would someone who can do C++ and English learn French faster? Can I learn English, PERL, Java, HTML, C, C++ and then learn Spanish much faster than someone who speaks only English?
As far as I understand it they are split into two categories: natural languages (English, Spanish, etc.) and formal languages (mathematics, c++, etc.). And from what I understand having knowledge form one group generally does not help you with knowledge or speed of learning in another group.
The structure and formulation of the types of language mean that you would probably use different parts of your brain to process them.
Also, from experience: I can learn a new programming language relatively quickly, while I struggle with second and third natural languages.
Also, learning a formal language is a lot simpler (IMHO) because there is less to learn and it is far less ambiguous and there are no exceptions (lol, I see what I did there).
Would someone who can do C++ and English learn French faster? Can I learn English, PERL, Java, HTML, C, C++ and then learn Spanish much faster than someone who speaks only English?
I don't believe it would help you learn Spanish a lot faster.
But there is some evidence that the brain's of people who program (at least from an early age) contain structures which parallel those exhibited by bilinguals. Based on this, it would suggest that your brain will be better set up to learn another natural language if you'd been programming for a while. Though prob. not a lot better, sadly (Well, I'm trying to learn French and still find it hard after quite a lot of programming.)