I'm new to mlr3 and R.I'm try to adjust parameter for surv.svm, but I can define the ParamSpace by paradox,because the type of
gamma.mu is ParamFct. This is my code:

svm<- lrn("surv.svm")

ps = ParamSet$new(params = list(ParamDbl$new(id = 'bound',lower = 5, upper=15),
ParamFct$new(id = 'opt.meth',levels = c("quadprog","ipop")),
ParamDbl$new(id = 'margin',lower = 0, upper=0.2),
ParamUty$new(id='gamma.mu'),(how to code gamma.mu?)
ParamFct$new(id = 'kernel',levels = c("lin_kernel","add_kernel","rbf_kernel","poly_kernel"))))
at= AutoTuner$new(learner =svm,
resampling = rsmp("holdout"),
measure = msr("surv.cindex"),
terminator = trm("evals", n_evals = 5),
tuner = tnr("random_search"),
search_space=ps)

Thank you！