Pitch: Implicit Returns from Single-Expression Functions

DevAndArtist · March 22, 2019, 8:06am

Excuse me? Can I ask why my proposal of the exact same thing was pushed back so hard especially by @Chris_Lattner3 back then? I appreciate all the work that author has done on this proposal but he missed the historical research on why this was not pushed forward so far.

By this comment this feature was simply put onto the bookshelf for many many years until Swift evolved so much that there is not much to add except convenient sugar:

[Proposal] [Stage–2] `return` consistency for single-expressions

Beyond that, though syntactic sugar is always motivated by strong rationale and use-cases, in my opinion, it is the most dangerous kind of additive feature to consider at this point of Swift’s evolution. While these features are useful, they also clearly add complexity to the language, and it is difficult to gauge whether the problem being addressed will even exist in Swift as the other bigger features come in (for example, a macro system). These features can also make future language evolution more problematic because they consume syntactic real estate in the language.

If you’re into analogies, I see features like the generics improvements, ownership model, concurrency model, macro system, new frameworks, and other large scale efforts as the “bricks" that make up the house of Swift. In that analogy, syntactic sugar proposals are “mortar” that fills in the cracks between the bricks. If we add too much mortar too early on, we run the risk of the house of Swift being built out of mortar, or of not being able to fit the bricks into the right places. That would be very bad, given that we all want the house of Swift to be strong and beautiful over the long term.

-Chris

The same proposal long time ago, before an implementation was required:

github.com

DevAndArtist/swift-evolution/blob/single_expression_optional_return/proposals/nnnn-single-expression-optional-return.md

# `return` consistency for single-expressions

* Proposal: [SE-NNNN](https://github.com/apple/swift-evolution/blob/master/proposals/nnnn-single-expression-optional-return.md)
* Author: [Adrian Zubarev](https://github.com/DevAndArtist)
* Status: **[Awaiting review](#rationale)**
* Review manager: TBD

## Introduction

Any single-expression closure can omit the `return` statement. This proposal aims to make this feature more consistent in some other corners of the language.

Original swift-evolution thread: 
* [\[Pitch\] \[Stage-2\] `return` consistency for single-expressions](https://lists.swift.org/pipermail/swift-evolution/Week-of-Mon-20170213/032153.html)
* [\[Pitch\] (Bofore Swift 3) Make `return` optional in computed properties for a single case](https://lists.swift.org/pipermail/swift-evolution/Week-of-Mon-20160523/019260.html)

## Motivation

Closures can omit the `return` and have an inferred return type:

```swift

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To be clear with everyone, I'm not trying to flame here nor do I put a brick in front of this proposal, as I proposed it myself already a few times, but I'm a little bit speechless and as I mentioned above already I appreciate the work from the current author.

Other than that, I'm +1 on this.