# \[Pitch\] Last expression as return value

**URL:** <https://forums.swift.org/t/pitch-last-expression-as-return-value/76958>\
**Category:** Pitches\
**Created:** [January 2, 2025, 12:37am UTC](https://forums.swift.org/t/pitch-last-expression-as-return-value/76958 "2025-01-02T00:37:10Z")\
**Posts on this page:** 1\
**Showing post:** 183

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**Author:** ![ben-cohen](https://sea2.discourse-cdn.com/swift/user_avatar/forums.swift.org/ben-cohen/32/296_2.png) [@ben-cohen](https://forums.swift.org/u/ben-cohen)\
**Post date:** [January 7, 2025, 12:50am UTC](https://forums.swift.org/t/pitch-last-expression-as-return-value/76958/183 "2025-01-07T00:50:17Z")

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> [@cmcfarlen](#):
>
> In swift, perhaps this might look like:
> 
> ```swift
> let foo = if x.isOdd {
> do {
> print("x was odd")
> x + 1
> }
> } else {
> x
> }
> 
> ```

This is a really interesting thought! In a way, it's a similar solution to the `then` keyword proposal, but instead applying the "last statement is the expression value" rule _only_ to `do` expressions, not more widely.

This has the big win of not requiring a keyword like `then` (and also eliminates the awkward parsing ambiguities).

Of course, it doesn't make everyone happy:

- simple closures still need fiddling with just to add a second trivial statement, so it doesn't make people who are enthusiastic about this proposal happy
- it still has an implicit last value rule for `do` expressions, which some folks will still find too subtle

Taking a step back for a second: speaking personally, my main goal is to lift the major limitation on `if`/`switch` expressions, and to introduce `do` expressions to replace the somewhat odd immediately executed closure idiom (and allowing for nice syntax for assigning results from either values or caught errors)

I feel like solving both these issues is an imperative for Swift. Inaction would be bad.

_How_ they are solved though is where there are options. So far we have a continuum:

- Introduce a new yielding keyword like `then`
- Introduce `do` expressions with a last expression rule, use them to solve the `if`/`switch` limitation
- Use trivia like `;` as Rust does
- Introduce a last expression rule for `if`, `switch`, `do`, but not functions/closures
- Go all in on a last expression rule

Of all of these options, using `;` is the only one I'm firmly against. I would be fairly happy with all 4 of the other outcomes. I'm currently warmest towards the full on last-expression rule, and I actually think the `do` option may be better than the keyword option.

edit: realized I was missing a middle ground option

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