const where = (...funcs) => {
    const bindings = funcs.reduce((vars, f) => ({
        ...vars, ...f(vars)
    }), {})

    return ({
        in: f => f(bindings)
    })
}

where(
    () => ({ x: 3 }),
    ({ x }) => ({ y: x * x })
).in(({ x, y }) => console.log('X', x, 'Y', y)) // prints `X 3 Y 9`