Presumably, to consider productivity the purpose is to get the most bang (output) for your buck (input).
The cost, C, to create app, A, that generates income I, varies with the pool of talent that will actually do the work. Also, consider the entropy of the system A targets, the C to modify A, and the time value of I. Once complete, if your org can live that long, if your A is faster, higher quality, more pleasurable to use, more cachet, more media coverage, more support, more money, more envy than a set of competitors, then the language it's written in becomes the next hot thing--if the word gets out.
Anyway, the ability for a junior programmer to pick up the code, create valuable improvements and grow with the organization (a super-specialized language requiring continual self-training is counter to that quality), and be productive, is a very important factor sometimes. So output can include very many, different things.
Function points may correlate to lines of code. If that's the case, then also consider the lines of code does not necessarily correlate with output. For instance, having to guess the correct search term to find the library you are needing to write that one line also takes time. Making sure the version of the library you are using plays nice with other libraries, the language syntax targets the version of the compiler, interpreter, hardware, architecture, platform, kernel, and standards also impacts output.
It is an interesting attempt to measure productivity with function point analysis. But, and you knew that was coming, there are so many more factors involved before you it is justifiably reasonable to draw a conclusion on productivity of a language.
The cost, C, to create app, A, that generates income I, varies with the pool of talent that will actually do the work. Also, consider the entropy of the system A targets, the C to modify A, and the time value of I. Once complete, if your org can live that long, if your A is faster, higher quality, more pleasurable to use, more cachet, more media coverage, more support, more money, more envy than a set of competitors, then the language it's written in becomes the next hot thing--if the word gets out.
Anyway, the ability for a junior programmer to pick up the code, create valuable improvements and grow with the organization (a super-specialized language requiring continual self-training is counter to that quality), and be productive, is a very important factor sometimes. So output can include very many, different things.
Function points may correlate to lines of code. If that's the case, then also consider the lines of code does not necessarily correlate with output. For instance, having to guess the correct search term to find the library you are needing to write that one line also takes time. Making sure the version of the library you are using plays nice with other libraries, the language syntax targets the version of the compiler, interpreter, hardware, architecture, platform, kernel, and standards also impacts output.
It is an interesting attempt to measure productivity with function point analysis. But, and you knew that was coming, there are so many more factors involved before you it is justifiably reasonable to draw a conclusion on productivity of a language.