`->` has a scoping bug

[klmr]

Needs investigation. The following two pieces of code should be equivalent but aren’t:

lambda = function (x) {
    mod::import('klmr/functional/lambda', '<-')
    lapply(seq_along(x), i -> x[i])
}

lambda2 = function (x) {
    mod::import('klmr/functional/lambda', '<-') # For consistency with the above
    lapply(seq_along(x), function (i) x[i])
}

Called as:

lambda(1 : 5)
lambda(1 : 5)

The second implementation works as expected; the first works for the first time, but fails when called again with:

Error in match.fun(FUN) : object 'i' not found

To make matters worse, the error vanishes when the function is being debugged. It also vanished if the mod::import call is pulled out of the function into the global namespace.