function foo1(f: (s: string) => string)
{
    return f("hello world");
}

function foo2(f: (s: number) => number)
{
    return f(123);
}

function genericBar<T extends string>(arg: T): T
{
    return arg;
}

var x1 = foo1(genericBar);
var x2 = foo2(genericBar);

function nonGenericBar(arg: string)
{
    return arg;
}

var y1 = foo1(nonGenericBar);
var y2 = foo2(nonGenericBar);  // Type error