Meaning of <bytecode: #> in R's built-in function definitions

Question

What does <bytecode: 0x02b59ae4> in below code mean ?

> nchar
function (x, type = "chars", allowNA = FALSE, keepNA = FALSE) 
.Internal(nchar(x, type, allowNA, keepNA))
<bytecode: 0x02b59ae4>
<environment: namespace:base>`

is it useful for anything ?

Answer 1

The bytecode statement indicates that the function has been byte compiled by the compiler package. All base R functions are byte compiled. Byte compiled functions are almost always faster than the non-compiled version.

If a package has a ByteCompile: true in its DESCRIPTION file, all functions in the package will be byte-compiled.

You can compile your own functions if you want:

f = function(x) x
f_cmp = compiler::cmpfun(f)
f
# function(x) x
f_cmp
# function(x) x
# <bytecode: 0x7f371a8>

Alternatively, you can set R_COMPILE_PKGS=3 in your .Renviron and that will byte-compile package on installation. This assumes you are installing the package from source.