I found entries on this site about learning a new programming language, however, I have not come across anything that talks about the advantages and disadvantages of learning two languages at the same time.

Let's say my goal is to learn two new languages in a year. I understand that the definition of learning a new language is different for everyone and you can probably never know everything about a language.

I believe in most cases the following things are enough to include the language in your resume and say that you are proficient in it (list is not in any particular order):

• Know its syntax so you can write a simple program in it
• Compare its underlying concepts with concepts of other languages
• Know best practices
• Know what libraries are available
• Know in what situations to use it
• Understand the flow of a more complex program
• At least know most of what you do not know

I would probably look for a good book and pick an open source project for both of these languages to start with.

My questions:

1. Is it best to spend 5 months learning language#1 then 5 months learning language#2, or should you mix the two. Mixing them I mean you work on them in parallel.

2. Should you pick two languages that are similar or different? Are there any advantages/disadvantages of let's say learning Lisp in tandem with Ruby? Is it a good idea to pick two languages with similar syntax or would it be too confusing?

Please tell me what your experiences are regarding this. Does it make a difference if you are a beginner or a senior programmer?