What is the function of the は + ない structure in「初デートで本屋はないだろ」?


Context: <https://streamable.com/det3c2>

> 初デートで本屋はないだろ

what is the meaning of this は + ない?




Not sure if you've noticed but there is a similar phrase that occurs in your
video clip prior to the line you are asking about.

> A: そんなに笑うことないだろ
>
> B: だって、お前初デートで本屋はないだろ

These two lines employ similar grammar structures. 「することはない」means there is no
need to do something. See [this
answer](https://japanese.stackexchange.com/a/1594/30454) for example. You
didn't ask about this construction so I guess you may be familiar with it.

The second one, which you are asking about, is structurally and semantically
similar.「～はない」structurally tells us the thing being discussed doesn't usually
happen or shouldn't happen. A similar phrase is「それはない」, see
[デジタル大辞泉（小学館）](https://dictionary.goo.ne.jp/word/%E5%85%B6%E3%82%8C%E3%81%AF%E3%81%AA%E3%81%84/):

> 相手の言動を強く非難・否認するときに用いる言葉。それはいけないよ。それはだめだよ。「今日になって行けないなんて、其れはないでしょう」

Also this structure is often followed by 「でしょう」「だろう」. Your line at issue can
be rendered as

> (Because) nobody goes to a bookstore on a first day.

If you look at the first structure, it shares the same pattern. Although in
English there is a difference between "You shouldn't do that" and "You don't
need to do that," in Japanese that distinction is more refined and context-
dependent. I feel like it behooves this discussion to quote Tsuyoshi Ito's
words from that answer:

> I wrote “on its face value” because if someone chooses to say that something
> is unnecessary, it is often because he/she actually thinks that something
> should not be done.
> ([source](https://japanese.stackexchange.com/a/1594/30454))

