What's the difference between a list and a vector whose mode is list?

Question

Title essentially says it all. I'm having trouble figuring out the difference between initializing a vector with vector(mode="list") and a list with list().

There are some minor differences in the signatures, list() can take value arguments or tag = value arguments whereas vector() cannot.

And then there's the following quote from the list() documentation:

Almost all lists in R internally are Generic Vectors

So is there any actual difference beside the fact that lists can be initialized with tags and values?

Answer 1

I'd say they're the same:

identical(list(),vector(mode="list", length=0))
## [1] TRUE

(see also this question about the confusing fact that a list is a vector in R: usually when R users refer to "vectors", they actually mean atomic vectors ...)

In my experience the most common use case for vector(mode="list",...) is when you want to initialize a list with length>0. vector(mode="list",10) might be a little more expressive than replicate(10,NULL). If you want to create a length-0 list I can't see any reason to use vector() instead of list().