How to save and load a splinefun object in R?

Question

I have been using the splinefun function in R to create a smooth interpolation between some data x and y. For example:

x <- 1:10
y <- x^2
f <- splinefun(x, y)
f(seq(1, 10, by = 0.1))

Now assume that obtaining y from x is time-consuming. The two highly-related questions are:

1. How can I save and load the function f from one R session to another without re-evaluating (or re-reading from a table) x and y?

2. How can I include f as part of an R package without evaluating/reading in each load x and y?

I know that this changed from R 3.0.0 and now f is saved inside a specific environment

environment(f) # <environment: 0x1036daf80>

and has the bytecode <bytecode: 0x1036e0748>, but no idea what to do with that.