Add explanation about how Rust's postfix await syntax is ergonomic#262
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nt54hamnghi wants to merge 2 commits into
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Add explanation about how Rust's postfix await syntax is ergonomic#262nt54hamnghi wants to merge 2 commits into
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Just one comment on the examples, otherwise looks good, thanks!
| In Rust, the syntax for using await is `some_future.await`, i.e., it is a postfix keyword used with the `.` operator. That means it can be used ergonomically in chains of method calls and field accesses. This is in contrast to languages like Python or JavaScript, where `await` is a prefix operator placed before an expression, such as `await some_function()`. | ||
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| Consider the following functions: | ||
| To see why postfix await is often more ergonomic, suppose you're calling an async function that makes a network request and want to access the status code of the response. With the prefix `await` syntax, you would need to prepend `await` to `fetch()`, then wrap the expression in parentheses to access the status code, like `(await fetch()).status_code`. In Rust, you can write `fetch().await.status_code?`. This becomes especially helpful in longer chains. E.g., an expression with two prefix awaits looks like `(await (await fetch()).json()).data`, whereas the Rust equivalent is `fetch().await.json().await.data?`, which reads more naturally. |
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The postfix versions a have a ?, but the prefix ones don't. For the ?s to be really significant, they need to be after the await rather than the field access. For the prefix versions they could be used after the parens.
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Thanks! I'll add ? after .await for the postfix versions.
For the prefix versions, should these be treated as hypothetical Rust prefix syntax, or syntax from languages that actually use it? My initial intent was to use valid Python so the syntax is recognizable, but I'm happy to change it. Just want to make sure we're aligned.
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