Understanding 行ってどうすんだ


> 「ねー、つれてってよ。七夕だよ」  
>  Hey, take me along. It's Tanabata.  
>  「七夕なんて **行ってどうすんだ** よ。毎年同じような飾りばっかりじゃねェか。今年はいいにしろ」  
>  Go to Tanabata _and do what?_ It's just the same decorations every year.
> Even if they're good this year...

I'm struggling to understand the 行ってどうすんだ part. I assume it's a contraction of
行ってどうするのだ, but I don't know what the function of どうする is here. Why is it not
marked as a question with ?/か

Does it mean "what will you do if you go?". I guess I would have said
something like:

> 言ったらどうするの？ 言ったらどうしよう？ or something like that

Would this be correct? Does it have the same nuance?

I can't understand how the て-form is being used in a place where I would have
expected an 'if'.




> 「行ってどうすんだ」＝「行ってどうす **る** んだ」,

just to confirm the dictionary form first.

> 「Verb in て-form + どうする + （の/んだ/んだよ, etc.）」

needs to be remembered as a set phrase because it is used _**heavily**_.

This expression actually means along the lines of:

> " _ **There is no use (verb + ing)**_." or
>
> " _ **What's the use of (verb + ing)?**_ "

rather than the literal:

> "You (verb) and then do what?"

Finally,

> "I can't understand how the て-form is being used in a place where I would
> have expected an 'if'."

That usage of 「て」 is common even outside of the set phrase we are talking
about. You can say:

「日本に行って、何をしたいの？」, which is basically the same thing as saying:

「日本に行ったら、何をしたいの？」




> 「行ってどうすんだ」＝「行ってどうす **る** んだ」,

just to confirm the dictionary form first.

> 「Verb in て-form + どうする + （の/んだ/んだよ, etc.）」

needs to be remembered as a set phrase because it is used _**heavily**_.

This expression actually means along the lines of:

> " _ **There is no use (verb + ing)**_." or
>
> " _ **What's the use of (verb + ing)?**_ "

rather than the literal:

> "You (verb) and then do what?"

Finally,

> "I can't understand how the て-form is being used in a place where I would
> have expected an 'if'."

That usage of 「て」 is common even outside of the set phrase we are talking
about. You can say:

「日本に行って、何をしたいの？」, which is basically the same thing as saying:

「日本に行ったら、何をしたいの？」

