Learning to program in a given language requires a non-trivial amount of time. This seems to be agreed upon as a good use of LessWrongers' time.
Each language may be more useful than others for particular purposes. However, like e.g. the choice of donation to a particular charity, we shouldn't expect the trade-offs of focusing on one versus another not to exist.
Suppose I know nothing about programming... And I want to make a choice about what language to pick up beyond merely what sounds cool at the time. In short I would want to spend my five minutes on the problem before jumping to a solution.
As an example of the dilemma, if I spend my time learning Scheme or Lisp, I will gain a particular kind of skill. It won't be a very directly marketable one, but it could (in theory) make me a better programmer. "Code as lists" is a powerful perspective -- and Eric S. Raymond recommends learning Lisp for this reason.
Forth (or any similar concatenative language) presents a different yet similarly powerful perspective, one which encourages extreme factorization and use of small well-considered definitions of words for frequently reused concepts.
Python encourages object oriented thinking and explicit declaration. Ruby is object oriented and complexity-hiding to the point of being almost magical.
C teaches functions and varying abstraction levels. Javascript is more about the high level abstractions.
If a newbie programmer focuses on any of these they will come out of it a different kind of programmer. If a competent programmer avoids one of these things they will avoid different kinds of costs as well as different kinds of benefits.
Is it better to focus on one path, avoiding contamination from others?
Is it better to explore several simultaneously, to make sure you don't miss the best parts?
Which one results in converting time to dollars the most quickly?
Which one most reliably converts you to a higher value programmer over a longer period of time?
What other caveats are there?
I haven't seen this advice before. A link would be appreciated.
Edit: The post has been retitled to "what is the best programming language". My main reason for doing so is to avoid confusion as well as dilution of the meaning of the word "rational" -- which should probably be reserved for specific contexts (e.g. avoiding cognitive biases) rather than used as a catch-all for "most optimal" and so forth.
My needs? Well I am already moderately skilled at a dozen or so languages, including Python, SQL, and Forth. My first scripting language was Perl and my first GUI language was REALBasic, which was essentially Visual Basic for the Mac.
Why did I go into Forth? Well, I wanted some down and dirty understanding of what the heck is actually going on in a computer. And I couldn't stick with C long enough to get that for some reason. Now I've done things like creating my own string manipulation functions (by concatenating other functions and primitives). I'm not sure I could have got that from Python.
On the other hand, now when I look at C code slinging pointers and char arrays around it makes perfect sense, and I can also visualize linked lists and other data structures. As a newbie though I remember it was all extremely confusing.
Behold, rational wart removal