originalEval = eval;
evaluate.onclick = function() {
  eval = originalEval;
  for (let s of document.getElementsByClassName("source")) {
    eval(s.value);
  }
}

document.documentElement.addEventListener("keypress", event => {
  if (event.key !== "Enter" || !event.shiftKey) return;
  event.preventDefault();
  document.getElementById("evaluate").click();
})

output.clear = function() {
  output.value = "";
}
output.log = function(a) {
  output.value = output.value + a + "\n";
}

env = {};
clearenv = function() {
  env = {};
}

temp.clear = function() {
  temp.innerHTML = "";
}
make_adder = function(b) {
  return function(t, id) {
    var a = document.createElement(t);
    a.id = id;
    a.add = make_adder(a);
    b.appendChild(a);
    return a;
  }
}
temp.add = make_adder(temp);

function clear() {
  clearenv();
  temp.clear();
  output.clear();
}

addsource.onclick = function() {
  let a = document.createElement("textarea");
  a.classList.add("source");
  a.rows="30";
  a.cols="60";
  sourceend.insertAdjacentElement("beforebegin", a);
}