Learn Hardcore Turkish: Salon boşken prova yapalım. - Let’s rehearse while the hall is empty.

With adjectives/nouns: boşken, gençken (when young), öğrenciyken (when a student), evdeyken (when at home), yokken (when absent/when nobody is there).
It’s tenseless by itself; the main verb supplies the time reference.

Do I need an explicit “to be” (like “is”) in boşken?

No. Turkish often omits a separate “to be” in the present. boşken already carries the idea of “(it is) empty.” It literally comes from boş iken, with iken contracting to -ken.

When do I insert the buffer consonant -y- in -(y)ken?

If the preceding word ends in a vowel, insert -y-: iyi → iyiyken, öğrenci → öğrenciyken.
If there’s a case ending ending in a vowel, you also use -y-: evde → evdeyken, işte → işteyken, Ankara’da → Ankara’dayken.
If it ends in a consonant, no -y-: boş → boşken, hazır → hazırken, yok → yokken.

Why is it salon boşken and not salondayken?

salon boşken = “when the hall is empty” (the hall’s state is empty).
salondayken = “when (someone) is in the hall” (location).
Use salon boşken to focus on the hall being empty; use salondayken to focus on being located in the hall.

What exactly does yapalım express?

It’s the 1st person plural optative/imperative: “let’s do/make.”
Breakdown: yap- (do/make) + -alım/-elim (let’s; vowel harmony). So prova yapalım = “let’s rehearse.”

Where is the subject “we” (biz)?

It’s built into the verb ending -alım/-elim. Turkish doesn’t need the pronoun unless you want emphasis or contrast. Biz is optional: Biz prova yapalım (we, as opposed to others).

How do I make it negative (“let’s not …”)?

Insert the negative -ma/-me before the optative: yap-mayalım = “let’s not do.”
Examples: gitmeyelim (let’s not go), konuşmayalım (let’s not talk).

Why say prova yapmak? Is there a single verb for “rehearse”?

Turkish commonly uses “noun + yapmak/etmek.” The most natural is prova yapmak. You’ll also hear:

prova etmek (also fine)
In theatre: prova almak (“run/take a rehearsal”)
More general “practice”: çalışma yapmak or simply çalışalım (“let’s practice”).

Is prova the object here? Why no accusative -ı?

Yes, it’s an indefinite direct object, and indefinite objects typically take no accusative: prova yapalım (“let’s rehearse [some]”).
Use the accusative when it’s specific/definite: provayı yapalım (“let’s do the rehearsal [the particular one we planned]”).

Can I change the word order?

Yes. Common variants:

Salon boşken, prova yapalım. (neutral, time clause first)
Prova yapalım, salon boşken. (afterthought/emphasis)
Prova yapalım salon boşken. (informal; a comma often helps clarity) The meaning stays the same; fronting the time clause emphasizes the condition.

How is boşken different from boş olduğunda, boş olunca, and boşsa?

boşken: while/whenever it is in the state of being empty (state-focused).
boş olduğunda: when it is empty/whenever it is empty (more formal/explicit).
boş olunca: when/once it becomes empty (sequence/change into emptiness).
boşsa: if/assuming it is empty (conditional, not guaranteed).

Does -ken attach to verbs too?

Yes:

beklerken (while waiting), çalışırken or çalışıyorken (while working), gelirken / geliyorken (while coming).
Forms with -yorken highlight an ongoing action; the shorter -irken forms are also common and idiomatic.

If I mean “as long as it’s empty,” what should I use?

Use -dığı sürece:

boş olduğu sürece = as long as it is empty
Stronger focus on duration: boş kaldığı sürece (as long as it stays/remains empty)

How can I make the suggestion softer or more polite?

Prova yapalım mı? (Shall we rehearse?)
Hadi prova yapalım. (Come on, let’s rehearse.)
Prova yapsak mı? (Maybe we should rehearse?)
İstersen(iz) prova yapalım. (If you like, let’s rehearse.)

How do I pronounce the dotless ı in yapalım and ş in boşken?

ı is a close, unrounded vowel (no exact English equivalent). Think of a quick, relaxed vowel like the second vowel in “roses” or the ‘a’ in “sofa”: ya-pa-lım.
ş is “sh” as in “shoe”: boş ≈ “bosh.”

Is the time reference now or future?

The -ken clause itself is tenseless. With yapalım, it usually suggests an immediate or near-future plan. It can also state a general rule (“whenever the hall is empty, let’s rehearse”).

Could I use the conditional -sa/-se instead of -ken?

Yes: Salon boşsa, prova yapalım. That reads “If/when the hall is empty, let’s rehearse.” It sounds slightly more conditional (it might or might not be empty), whereas boşken frames it as a state during which the action should happen.