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Comment by hibbelig | Hacker News Reader

I can't think of an example where

    let x = <something>;

compiles but

    <something>;

does not compile. I think all expressions are statements.

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Some languages forbid "obviously pure" expressions like "0" as statements (since using them as a statement is probably a mistake).

Interesting! Any examples of such languages?

Java is one popular example. You get "error: not a statement".

I think I was saying that Javascript is not one of them.

Right. They're not mutually exclusive -- hence the "both, either, or neither"

My point was that there are four combinations, and "both, either, or neither" suggests that all four can happen. But actually, only three out of four can happen.

It can be both a statement and an expression. Yes.

It can be neither a statement nor an expression. Yes.

It can be a statement but not an expression. Yes.

But the case that it is an expression but not a statement: this case never happens.

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