Simple MLState Opa Calculator.

easycalc.opa

function sum()
{
  a = Int.of_string(Dom.get_value(#vala));
  b = Int.of_string(Dom.get_value(#valb));
  #res = a + b; 
}

function start() {
  <div>EasyCalc</div>
  <div>
    <input id=#vala type="text"/> + <input id=#valb type="text"/>
    = <p id=#res/>
    <input type="button" value="Add" onclick={function(_) { sum()}}/>
  </div>
}

Server.start(
  Server.http,
  [ {title: "Hello World", page:start} ]
);