namespace $Eval {
    var cache = Map();
    var evalResult;
}

fun evalInContext(code: str, context: Map) -> any {
    var str = "$Eval.evalResult = (context) {\n";
    for(var k in context.keys){
        str += "\tvar ${k} = context['${k}'];\n";
    }
    str += "\treturn (${code});\n";
    str += "}";
    var func = $Eval.cache[str];
    if(func == null){
        print(str);
        eval(str);
        func = $Eval.evalResult;
        $Eval.cache[str] = func;
        $Eval.evalResult = null;
    }
    return func(context);
}

print(evalInContext("a + b", {a:1,b:2}));
print(evalInContext("a + b", {a:2,b:3}));
print(evalInContext("a + b", {a:3,b:4}));
print(evalInContext("a + b + c", {a:3,b:4, c:6}));
print(evalInContext("a + b + c", {a:3,b:4}));

namespace $Eval  {
  var cache = Map();
  var evalResult;
}
fun evalInContext(code: Instance of 'IdentifierExpr', context: Instance of 'IdentifierExpr') -> Instance of 'IdentifierExpr'  {
  var str = $Eval.evalResult = (context) {\n;
  for (var k in context.keys)  {
    str = str + '\tvar ${k} = context['${k}'];\n'
  }
  str = str + '\treturn (${code});\n'
  str = str + }
  var func = $Eval.cache[str];
  if (func == null)  {
    print(str)
    eval(str)
    func = $Eval.evalResult
    $Eval.cache[str] = func
    $Eval.evalResult = null
  }
  return func(context);
}

print(evalInContext(a + b, {
a: 1,
b: 2
}))
print(evalInContext(a + b, {
a: 2,
b: 3
}))
print(evalInContext(a + b, {
a: 3,
b: 4
}))
print(evalInContext(a + b + c, {
a: 3,
b: 4,
c: 6
}))
print(evalInContext(a + b + c, {
a: 3,
b: 4
}))