Generates a Pascal's Triangle

pascal.erl

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

% Generates a Pascal's Triangle
% 1. Start Erlang interpreter in folder with this file
% 2. Do: c(pascal).
% 3. Do: pascal:triangle(5).
% Which would create a Pascal's Triangle 5 lines deep.

% calculate factorial
fact(0) -> 1;
fact(N) when N > 0, is_integer(N) -> N * fact(N-1).

% calculate binomial coefficient of N choose R
bin_coef({N, R}) ->
  fact(N) div (fact(N-R) * fact(R)).

% draw a line N integers wide
draw_line(0) ->
  io:format("~B~n", [1]);
draw_line(1) ->
  io:format("~B ~B~n",[1,1]);
draw_line(N) ->
  Elements = lists:zip(lists:duplicate(N+1, N), lists:seq(0, N)),
  Line = [bin_coef(L) || L <- Elements],
  lists:map(fun(I) -> io:format("~B ", [I]) end, Line),
  io:format("~n").

% draw pascal's triangle
triangle(N) ->
  Lines = lists:seq(0, N), 
  [draw_line(L) || L <- Lines].