Can やら be considered a casual substitute for か?


In trying to understand the word やら, I have seen various example sentences
where it is used the same way you might use か.

> 彼は何と言ってよいのやらわからなかった。
>
> いつの間にやら日が暮れていた。
>
> 彼が何やら言っているがよく聞こえない。
>
> 彼は来るのやら来ないのやらはっきりしない。

I feel like in all the above sentences, if やら was replaced with か, the meaning
would be about the same, if perhaps a touch less casual. So would it be a
correct interpretation that やら is often used as a casual substitute for か?

Note that I wouldn't apply this rule to the other forms of やら (e.g. とやら,
〜やら〜やら, or 〜やら -- I wonder).




やら is definitely very similar in meaning to か, but, as you might expect from a
particle that's not etymologically related and thus developed separately,
there are distinctions in nuance and usage that make it hard to call them
perfectly equivalent.

The main semantic difference between the two is that やら provides a certain
deliberate emphasis on the speaker's uncertainty about whatever it's attached
to, whereas か is neutral and objective. You can think of it as something like
an implied 分からない included in the particle. The most obvious implication of
this is that やら can never be used to state an actual question in the way that
か can. 何をしているのか can be a direct question "what are you doing?", but 何をしているのやら
can only be a rhetorical one - you can almost hear an unstated さっぱり分からないね
following it.

In situations where か would not form a direct question, the implications of
this emphasis on uncertainty are more subtle and can vary somewhat. In many
cases the choice of やら implies dismissiveness, ie. that you're leaving a
question open because the answer is _unimportant_. For example, while
彼は何か(を)書いている is a very neutral statement that "he is writing something",
彼は何やら書いている sounds more like "he's writing something-or-other" - there's a
distinct implication that the speaker doesn't care what he's actually writing,
or can't be bothered to find out.

In other cases, the implication can be more straightforward unfamiliarity. For
instance, in fairly common expressions along the lines of 何やら面白いことになっている, the
choice of やら certainly isn't dismissive per se; if anything it indicates
curiosity, the idea that the speaker can't imagine _what_ is going on but it
certainly seems interesting. If it were 何か面白いことになっている the sense of uncertainty
would be weaker and less personal, so this form doesn't see as much usage.

Outside of this added subjective nuance, though, I would say that やら and か are
very close in meaning. Even the "other forms" you listed could be reasonably
substituted with か in one way or another. Something like 田中とやら "Tanaka or
whatever his name is" is roughly the same in meaning as 田中とかいうヤツ - the latter
can similarly be abbreviated to 田中とか, but the dismissive nuance of the phrase
is better suited to やら, so it's that form that has fossilised more
recognisably as a set expression. ～やら～やら as a way of listing things is
essentially equivalent to ～とか～とか, with the choice of やら providing only an
added sense of not caring much about the particulars. And ～やら "I wonder" is,
as I touched on above, simply the result of substituting やら for か in an actual
question, thus making it strictly rhetorical.




やら is definitely very similar in meaning to か, but, as you might expect from a
particle that's not etymologically related and thus developed separately,
there are distinctions in nuance and usage that make it hard to call them
perfectly equivalent.

The main semantic difference between the two is that やら provides a certain
deliberate emphasis on the speaker's uncertainty about whatever it's attached
to, whereas か is neutral and objective. You can think of it as something like
an implied 分からない included in the particle. The most obvious implication of
this is that やら can never be used to state an actual question in the way that
か can. 何をしているのか can be a direct question "what are you doing?", but 何をしているのやら
can only be a rhetorical one - you can almost hear an unstated さっぱり分からないね
following it.

In situations where か would not form a direct question, the implications of
this emphasis on uncertainty are more subtle and can vary somewhat. In many
cases the choice of やら implies dismissiveness, ie. that you're leaving a
question open because the answer is _unimportant_. For example, while
彼は何か(を)書いている is a very neutral statement that "he is writing something",
彼は何やら書いている sounds more like "he's writing something-or-other" - there's a
distinct implication that the speaker doesn't care what he's actually writing,
or can't be bothered to find out.

In other cases, the implication can be more straightforward unfamiliarity. For
instance, in fairly common expressions along the lines of 何やら面白いことになっている, the
choice of やら certainly isn't dismissive per se; if anything it indicates
curiosity, the idea that the speaker can't imagine _what_ is going on but it
certainly seems interesting. If it were 何か面白いことになっている the sense of uncertainty
would be weaker and less personal, so this form doesn't see as much usage.

Outside of this added subjective nuance, though, I would say that やら and か are
very close in meaning. Even the "other forms" you listed could be reasonably
substituted with か in one way or another. Something like 田中とやら "Tanaka or
whatever his name is" is roughly the same in meaning as 田中とかいうヤツ - the latter
can similarly be abbreviated to 田中とか, but the dismissive nuance of the phrase
is better suited to やら, so it's that form that has fossilised more
recognisably as a set expression. ～やら～やら as a way of listing things is
essentially equivalent to ～とか～とか, with the choice of やら providing only an
added sense of not caring much about the particulars. And ～やら "I wonder" is,
as I touched on above, simply the result of substituting やら for か in an actual
question, thus making it strictly rhetorical.

