If you are an analyst working for a bank, then your job is to do financial analysis to inform trading decisions. That is what your title is, that is the result you are expected to produce, that is what you will see yourself as. But to actually do that, you might be writing F# 40 hrs a week. You wouldn't consider yourself a programmer tho'. The program is not a product in and of itself; it's just a tool you use that you happen to also make yourself 'cos it's easier than writing a spec document and waiting for "a programmer" to do it.

Similarly if you are an engineer working for Ericcson on switches for telcos then you job is to design and implement switches. The result you are expected to produce is a switch that is better than the current one. You will probably see yourself as an electronic engineer - but you might actually be writing Erlang 40 hrs a week. The code isn't a product either - it's just the means by which you tell your switch hardware how to behave.

Whereas if you are a "PHP programmer" someone has already decided that PHP is what we're doing and your role is to do PHP and your end product is a website built with PHP. Which is not a bad thing mind - but it is why you see "PHP jobs" and you don't see so many "F# jobs".