lapply-ing with the “$” function

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This is documented in ?lapply, in the “Note” section (emphasis mine):

For historical reasons, the calls created by lapply are unevaluated,
and code has been written (e.g. bquote) that relies on this. This
means that the recorded call is always of the form FUN(X[[0L]],
...), with 0L replaced by the current integer index. This is not
normally a problem, but it can be if FUN uses sys.call or
match.call or if it is a primitive function that makes use of the
call. This means that it is often safer to call primitive functions
with a wrapper, so that e.g. lapply(ll, function(x) is.numeric(x))
is required in R 2.7.1 to ensure that method dispatch for is.numeric
occurs correctly.

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