What is the etymology behind したっけ


僕だけがいない街 anime shows the children saying したっけ! translated as 'See ya!' and
other terms, these are from Hokkaido dialect.

I guess you can switch したっけ to other forms to say 'See ya': じゃあまた また明日

Anyway, there's any relation with 明日? What is the etymology resulted in したっけ?

The way that したっけ sounds, it's like an affirmation than a question.




No, this phrase isn't cognate with Standard Japanese あした.

したっけ literally means what in Standard Japanese そうしたら. The demonstrative そう is
omitted because the whole context before is considered to stand in place of it
(colloquial omission of this そう is also common in Tokyo). The っけ part shares
the same origin with Standard
[っけ](http://dictionary.goo.ne.jp/jn/65853/meaning/m0u/%E3%81%91/) ("(what)
again?"), that is Classical indirect past
[けり](http://dictionary.goo.ne.jp/jn/68898/meaning/m0u/), but has diverged from
it to mean "(after it) then".

Thus, Hokkaido-ites say "Now then!" to mean "See you!", but this is exactly
parallel to Standard Japanese too, where さようなら literally means さよう ("so") + なら
("if be -- then") in older way of speaking.

**EDIT**  
したっけ is seemingly used in [the same meaning in Ibaraki dialect,
too](http://www.weblio.jp/content/%E3%81%97%E3%81%9F%E3%81%A3%E3%81%91).
Hokkaido dialect is a mish-mash of various Honshu dialects, so it's possible
that this part of grammar was exported from Northern Kanto.




No, this phrase isn't cognate with Standard Japanese あした.

したっけ literally means what in Standard Japanese そうしたら. The demonstrative そう is
omitted because the whole context before is considered to stand in place of it
(colloquial omission of this そう is also common in Tokyo). The っけ part shares
the same origin with Standard
[っけ](http://dictionary.goo.ne.jp/jn/65853/meaning/m0u/%E3%81%91/) ("(what)
again?"), that is Classical indirect past
[けり](http://dictionary.goo.ne.jp/jn/68898/meaning/m0u/), but has diverged from
it to mean "(after it) then".

Thus, Hokkaido-ites say "Now then!" to mean "See you!", but this is exactly
parallel to Standard Japanese too, where さようなら literally means さよう ("so") + なら
("if be -- then") in older way of speaking.

**EDIT**  
したっけ is seemingly used in [the same meaning in Ibaraki dialect,
too](http://www.weblio.jp/content/%E3%81%97%E3%81%9F%E3%81%A3%E3%81%91).
Hokkaido dialect is a mish-mash of various Honshu dialects, so it's possible
that this part of grammar was exported from Northern Kanto.

