Erlang : nested cases

I'm very new to Erlang. I tried to find out if a list index is out of bounds (before trying it) so i wanted to do an if clause with something like

if lists:flatlength(A) < DestinationIndex ....

I discovered that those function results cannot be used in if guards so i used case instead. This results in a nested case statement

case Destination < 1 of
    true -> {ok,NumberOfJumps+1};
    false ->
    case lists:flatlength(A) < Destination of
        true -> 
            doSomething;
        false ->
            case lists:member(Destination,VisitedIndices) of
                true -> doSomething;
                false -> 
                    doSomethingElse
            end
    end
end.

I found this bad in terms of readability and code style. Is this how you do things like that in erlang or is there a more elegant way to do this?

Thanks in advance