I'm pretty sure the field is too young to have developed a standard unit of measurement of either of these things, if there were such units their creation would be one of the stunning intellectual achievements of mankind in recent history and would have such obvious benefits to many other parts of human endeavor that I would expect it would be a field more investment heavy than machine learning at the moment.
However it has been shown that there are people who seem more attuned to different learning styles, styles of programming, there are differences in difficulty between first language acquisition and later (dependent on language similarity, language domain), and many other studies regarding programming language learning that it can be said not everyone learns equally well every language, and not every language is equally as learnable.
> it can be said not everyone learns equally well every language, and not every language is equally as learnable.
I think that’s reasonable, but the question is then at what point does a language become sufficiently difficult that it no longer provides a good return on investment? And to what degree of proficiency must one achieve in a language in order to productively use it?
It doesn’t take a long time to learn all of Elm, and you can be productive in it quickly.
It takes a very long time to learn all of Haskell, but it does not take a very long time to be productive with it.
totally agreed, and I suppose in Paul Graham's concept of a Blub programming language there might be a language that is difficult to become proficient in but allows you to achieve things that would not be reasonably achievable in other languages.
However it has been shown that there are people who seem more attuned to different learning styles, styles of programming, there are differences in difficulty between first language acquisition and later (dependent on language similarity, language domain), and many other studies regarding programming language learning that it can be said not everyone learns equally well every language, and not every language is equally as learnable.