  The measurement of the production of single muons from heavy-flavour hadron
decays at forward rapidity in Pb--Pb collisions at $\sqrt{s_{\rm NN}} =
5.02~{\rm TeV}$ collected in 2015 is presented as a function of transverse
momentum ($p_{\rm T}$) and collision centrality. A strong suppression of the
yield is observed at high $p_{\rm T}$ in the most central collisions compared
to the binary-scaled expectation from pp collisions at the same energy. The
$p_{\rm T}$-integrated nuclear modification factor ($R_{\rm AA}$) as function
of the number of participating nucleons indicates an increase of the
suppression from peripheral to central collisions. Comparisons with the results
for Pb--Pb collisions at $\sqrt{s_{\rm NN}} = 2.76~{\rm TeV}$ and with
transport model predictions are shown. A similar suppression is measured at
both $\sqrt{s_{\rm NN}} = 2.76~{\rm TeV}$ and 5.02 TeV. The results available
from $p_{\rm T} =$7 GeV/$c$ up to $p_{\rm T} =~$20 GeV/$c$, will provide new
constraints on transport model ingredients and new insights on the
understanding of the evolution of the hot and dense matter formed in
ultra-relativistic heavy-ion collisions.
