More along functions?

[hadley]

I wonder if it would be useful to have:

list_along <- function(x) {
  vector("list", length(x)
}

rep_along <- function(x, y) {
   rep(x, length.out = length(y))
}

I find myself reaching for those functions (by analogy to seq_along()) fairly frequently

[hadley]

Could take multiple arguments and throw an error if they're not the same length?