Learn Farsi: در این بیابان نه آب هست نه غذا. - In this desert, there is neither water nor food.

When you use the na ... na ... (neither ... nor ...) structure in standard Farsi, the negative meaning is already fully carried by those conjunctions. Because of this, the verb is kept affirmative (using hast instead of the negative nist). While you might hear double negatives in casual spoken Farsi, using the affirmative verb is standard and elegant.

Why is hast in the middle of the phrase instead of at the very end?

While Farsi usually puts verbs at the end of the sentence, the na [A] ... na [B] ... structure is a bit flexible. It is very common to place the verb right after the first item to balance the sentence rhythmically. Saying na āb na ghazā hast (putting it at the end) is also grammatically correct, but placing it in the middle is highly natural.

Did we drop a second verb at the end of the sentence?

Yes! The full, literal thought would be na āb hast na ghazā hast (neither water exists, nor food exists). To avoid repeating the verb, Farsi drops the second hast, leaving just the noun at the end.

Is it possible to use ast instead of hast in this sentence?

No, because ast simply links a subject to an adjective or noun (like an equals sign, as in "the water is cold"). In this sentence, we need to express existence ("there is"). The verb hast acts as the verb of existence here, meaning "exists" or "there is/are".