Give it the candidates. Several arguments are one candidate each; a single
argument holding several values is the candidates, so a computed grid is
passed directly:
setup_LightRF(max_depth = tune_over(3L, 4L, 5L))
setup_LightRF(lambda_l2 = tune_over(10^seq(-4, 0, length.out = 5)))
setup_MLP(hidden_units = tune_over(c(12L, 6L, 2L), c(14L, 12L, 6L, 2L)))
For a vector-valued hyperparameter one candidate is itself a vector, so
pass the candidates as separate arguments or as a list --
tune_over(list(c(12L, 6L), c(24L, 12L))). A single bare vector there would
be one architecture, and is an error saying so.
Passing it to a hyperparameter that is not tunable is an error: that
hyperparameter accepts a value only.