Don't PL developers need to implement things like List.reverse() in their new languages all the time?
Rhetorical question, because I know the answer is yes.
Here's an example for Julia: https://github.com/JuliaLang/DataStructures.jl/blob/master/s...
function reverse{T}(l::LinkedList{T})
l2 = nil(T)
for h in l
l2 = cons(h, l2)
end
l2
end
The premise of your remark indicates the absurdity of the claim of relevance. An interview for a position responsible for writing a new language in a language sufficiently low level to require a new `list.reverse` would invariably require implementation of a list type as well...what language includes <List> without a reverse?
It's pretty well known that Google's hiring process for SDEs is designed to select for skilled computer scientists--the type of people who could do something like implement a stdlib for a new PL if needed. Then, since they can afford to hire only great all-around CS people, they can just allocate people to projects after the hiring decision is made. Of course not every SDE job at Google requires that level of CS skill, and it's massively wasteful to put most people on projects below their skill level, but they can afford to hire that way just because they're Google.
As a side effect, other companies hiring developers are likely to just cargo-cult whatever Google is doing.
The truth is that in a few hours, looking at some of the code base and discussing it is going to give both parties a better feel for the fit of person and job than anything else. The interviewer gets a feel for how the candidate will deal with the mess that is someone else's code and build process and the candidate gets a better feel for the mess they will be dealing with.