will/shall + infinitive
We use the future simple to express a promise.
They will allow you to go through.
He shall be present tomorrow at the meeting.
I will do my best.
We use the future simple to express a prediction about the future.
His birthday will bring much happiness to the people.
Next year will be a great surprise.
I don’t know what will happen if it doesn’t succeed.
The future simple is used to express a voluntary action, usually, it is used for a spontaneous decision right at the moment as we’re making it.
Can you help me, please? Yes, I will help you right this instant.
Could you send me the check, please? Yes, I will send it now.
He shall prepare your lunch sir.
He will make the order.
Note that, there are many similarities between will and the ‘be going to’ form. For instance, both can mean ‘an intention’, or ‘a prediction’.
‘I am going on vacation in March’. or ‘I will go on vacation in March’.
‘I think this man is going to be the next president’. or ‘I think this man will be the next president’.