$JSRTS.prim_systemInfo = function (index) {
    switch (index) {
        case 0:
            return "javascript";
        case 1:
            return navigator.platform;
    }
    return "";
};
$JSRTS.prim_writeStr = function (x) { return console.log(x) }
$JSRTS.prim_readStr = function () { return prompt('Prelude.getLine') };