Variables and patterns in practice

variables_patterns_exercise.erl

-module(variables_patterns_exercise).

-export([test/0]).

test() ->
  0 = how_many_equal(34,25,36),
  2 = how_many_equal(34,25,34),
  2 = how_many_equal(34,34,25),
  2 = how_many_equal(25,34,34),
  3 = how_many_equal(34,34,34),
  9 = maximum_of_three(3,6,9),
  100 = maximum_of_three(100,50,25),
  0.3 = maximum_of_three(0.1, 0.3, 0.2),
  true = x_or1(true, false),
  true = x_or1(false, true),
  false = x_or1(true, true),
  false = x_or1(false, false),
  true = x_or2(true, false),
  true = x_or2(false, true),
  false = x_or2(true, true),
  false = x_or2(false, false),
  true = x_or3(true, false),
  true = x_or3(false, true),
  false = x_or3(true, true),
  false = x_or3(false, false),
  ok.

x_or1(X, Y) -> not(X == Y).
x_or2(X,Y) -> X =/= Y.
x_or3(X,Y) -> (X or Y) and not(X and Y).

how_many_equal(X,X,X) -> 3;
how_many_equal(X,X,_Y) -> 2;
how_many_equal(X,_Y,X) -> 2;
how_many_equal(_Y,X,X) -> 2;
how_many_equal(_X,_Y,_Z) -> 0.

maximum_of_three(X,Y,Z) -> max(max(X,Y),Z).

Niiiice :)