You will write a simple calculator (sum, substraction, multiplication, and division) using processes and passing messages. For this you will write a module calculator and create the following functions:
start_calculator/0: This functions will spawn acalculator:calculator_server/1.calculator_server/0: It will receive through messages the operation to execute and its arguments, and send back the result.turn_off/1: Shuts down the calculator server.
This is the bare minimum you need to make a working example, but we won't stop there so will use what you learned in "We Love Messages, but we keep them secret" to abstract everything to simple functions the user can use without knowing about underlying protocol. For this create the functions: add/3, subtract/3, multiply/3, divide/3. This functions will receive as input PID and a tuple contaning the two numbers to operate on, send the message to the calculator server, and return the result.
1> Cal = calculator:start_calculator().
<0.67.0>
2> calculator:add(Cal, 1, 3).
4
3> calculator:subtract(Cal, 1, 3).
-2
4> calculator:multiply(Cal, 7, 3).
21
5> calculator:divide(Cal, 7, 3).
2.3333333333333335
6> calculator:divide(Cal, 0, 3).
0.0
7> calculator:divide(Cal, 2, 3).
0.6666666666666666
8> calculator:turn_off(Cal).
offCheck our proposed solution.