5 minute Erlang version:

  -module(pascal).
  -export([tri/1]).

  tri(Depth) ->
    tri(Depth,[[1]]).

  calc_row_rest([_]) ->
    [1];
  calc_row_rest([X,Y | Rest]) ->
    [X + Y | calc_row_rest([Y | Rest])].

  calc_row(Acc) ->
    [1 | calc_row_rest(Acc)].

  tri(X,_) when X =< 0 ->
    [];
  tri(1,Acc) ->
    lists:reverse(Acc);
  tri(Depth,Acc) ->
    NewRow = calc_row(hd(Acc)),
    tri(Depth-1,[NewRow | Acc]).

Returns a list of the pascal triangle rows:

  > pascal:tri(10).
  [[1],
  [1,1],
  [1,2,1],
  [1,3,3,1],
  [1,4,6,4,1],
  [1,5,10,10,5,1],
  [1,6,15,20,15,6,1],
  [1,7,21,35,35,21,7,1],
  [1,8,28,56,70,56,28,8,1],
  [1,9,36,84,126,126,84,36,9,1]]