RosettaCodeData/Task/Flatten-a-list/Maple/flatten-a-list-2.maple

flatten := proc(x)
  `if`(type(x,'list'),seq(procname(i),i = x),x);
end proc:

L := [[1], 2, [[3,4], 5], [[[]]], [[[6]]], 7, 8, []]:

[flatten(L)];