昨夜スーパーへ買い物しに行きました。

I understand the purpose of the "ni" particle, but why does it need the "shi"?
Did I miss something?

Thanks.
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2017-07-10T03:03:39.277
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2017-07-10T18:00:09.637
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question
grammar particles
What's the purpose of "し" after "買い物" in this sentence?
> What's the purpose of “し” after “買い物” in this sentence?  
>  昨夜スーパーへ買い物しに行きました。
>
> I understand the purpose of the "ni" particle, but why does it need the
> "shi"? Did I miss something?

It doesn't need, and must be colloquial, but not wrong. We say 買い物をしに行く,
買い物しに行く, or 買い物に行く. This し is just the conjugated version (連用形) of する. And に
is a particle to show a purpose of the action expressed by the following verb.

  * 食事しに行きませんか？ ＝食事に行きませんか？
  * 宿題しに友だちがもうすぐ来る。(I find this one is not very natural without this し.)
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2017-07-10T03:35:25.753
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answer
"に for purpose" can be used in two ways:

  * `masu-stem of any verb` + に 

> 泳ぎに行く, 食べに行く, 見に行く, 発表しに行く

  * `noun part of suru-verb` + に 

> 観劇に行く, 食事に行く, 発表に行く

The masu-stem (aka pre-masu form) of 買い物する is 買い物し, so that's where the し came
from. When you say "in order to (verb)" using a suru-verb and に, ○○に and ○○しに
are usually interchangeable.

に has many other roles, including as a destination marker (e.g., 学校に行く). ○○しに
is unambiguous and preferred when the word it modifies is remote.

>   * 買い物しにスーパーに行きました。
>   * [?] 買い物にスーパーに行きました。 (understandable, but clumsy)
>
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answer