Other uses of the たら conditional


Passing a verb to its past tense conjugation and adding ら makes the sentence a
condition, right? Like

> 暇だったら、遊びに行くよ - If I'm free, I will go to play.

But in the ももたろう tale the たら form is used differently in the sentence:

> ある日、 おばあさん が 川 で せんたく を して いたら、  
>  ももがながれて きました

The translation I found states that "one day, WHILE the old lady was at the
river doing the laundry a peach came floating by" so my question is: Is this
translation any good? Can the たら conditional be used to relate two actions
taking place at the same time? Can it be interpreted as 'while'?

Further ahead there's a sentence that says:

> ひろって たべたら、  
>  なんとも おいしくて ほっぺた が おちそう。

Which translates as: She picked it up and ate it and, it was so delicious as
if to make her cheeks fall.

So what is the role of たら here?

Thank you very much.




Your first understanding is correct. The other usages you give are also
correct and I would consider them good translations. While it is a
'conditional' it has a broader meaning than just 'if'. Like in the latter
examples it is also used to indicate an event that occurred unexpectedly as a
result of another action, or linked to it in some way. In such cases there's
an implication that without the first action, the second one wouldn't have
occurred and it was not anticipated that the second event would occur and
often when used like this it is translated as 'when' or 'while'.

For example:「一人で **歩いてたら** 、怖い男に話しかけられた。」ー”A scary guy approached me **when I
was walking** by myself.”

Here you can see there are two things - walking and being approached by
someone. It is implied that they would not have been approached had they not
been walking and it's as a result of being out walking by themselves that they
were approached and this was not expected to have happened.

In the last example you give たら is indicating that they were not expecting it
to be so delicious their cheeks fell off but when they ate it, they discovered
that was the case.

So as you can see in all these examples B is always 'conditional' on A.

