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Simplify note about functions in ch13-01-closures.md
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proski committed Jul 18, 2023
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11 changes: 5 additions & 6 deletions src/ch13-01-closures.md
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Expand Up @@ -332,12 +332,11 @@ called. If the `Option` is `None`, `f` will be called once. Because all
closures implement `FnOnce`, `unwrap_or_else` accepts the most different kinds
of closures and is as flexible as it can be.

> Note: Functions can implement all three of the `Fn` traits too. If what we
> want to do doesn’t require capturing a value from the environment, we can use
> the name of a function rather than a closure where we need something that
> implements one of the `Fn` traits. For example, on an `Option<Vec<T>>` value,
> we could call `unwrap_or_else(Vec::new)` to get a new, empty vector if the
> value is `None`.
> Note: Functions can be used in place of closures in some cases. For example,
> we could call `unwrap_or_else(Vec::new)` on a value of type `Option<Vec<T>>`.
> If the value is `None`, we would get a new, empty vector. It works because
> functions implement the `Fn` traits just like closures. However, only
> closures can capture variables from the enviroment, functions cannot do it.
Now let’s look at the standard library method `sort_by_key` defined on slices,
to see how that differs from `unwrap_or_else` and why `sort_by_key` uses
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