> On May 2, 2016, at 12:16 AM, David Hart via swift-evolution
> <[email protected]> wrote:
>
> Hello swift-evolution,
>
> I took the pitch originally from Developer to move the where clause out of
> the generic parameter list, with improvements brought up by Pyry Jahkola, and
> wrote a proposal for it. I opened a Pull Request, but if anybody wants to
> bring some modifications to it before it is merged, please let me know what
> you think:
>
> Move where clause to end of declaration
>
> Proposal: SE-XXXX
> <https://github.com/apple/swift-evolution/blob/master/proposals/XXXX-move-where-expression.md>
> Author(s): David Hart <https://github.com/hartbit>, Developer, Pry Jahkola
> <https://github.com/hartbit/swift-evolution/blob/move-where-clause/proposals/[email protected]>
> Status: TBD
> Review manager: TBD
>
> <https://github.com/hartbit/swift-evolution/blob/move-where-clause/proposals/XXXX-move-where-expression.md#introduction>Introduction
>
> This proposal suggests moving the where clause to the end of the declaration
> syntax, but before the body, for readability reasons. It has been discussed
> at length on the following swift-evolution thread:
>
> [Pitch] Moving where Clauses Out Of Parameter Lists
> <https://github.com/hartbit/swift-evolution/blob/move-where-clause/proposals/GMANE_DOWN_FOR_NOW>
>
> <https://github.com/hartbit/swift-evolution/blob/move-where-clause/proposals/XXXX-move-where-expression.md#motivation>Motivation
>
> The where clause in declarations can become quite long. When that happens, it
> breaks the declaration syntax in two, hurting its readability. There is also
> no good way of formatting the declaration syntax to make it much better.
>
>
> <https://github.com/hartbit/swift-evolution/blob/move-where-clause/proposals/XXXX-move-where-expression.md#proposed-solution>Proposed
> solution
>
> The proposal suggests moving the where clause at the end of the declaration,
> but before the body of concerned declarations. With the proposed change,
> where clauses do not impede the main declaration and are also more easily
> formattable. For example, here is the same function declaration before and
> after the change:
>
> func anyCommonElements<T : SequenceType, U : SequenceType where
> T.Generator.Element: Equatable,
> T.Generator.Element == U.Generator.Element>(lhs: T, _ rhs: U) -> Bool
> where
> {
> ...
> }
>
> func anyCommonElements<T : SequenceType, U : SequenceType>(lhs: T, _ rhs: U)
> -> Bool where
> T.Generator.Element: Equatable,
> T.Generator.Element == U.Generator.Element
> {
> …
Random minor comment: I find that putting the “where” at the end makes this
almost unreadable, and would very much have preferred
> func anyCommonElements<T : SequenceType, U : SequenceType>(lhs: T, _ rhs: U)
> -> Bool
> where T.Generator.Element: Equatable, T.Generator.Element ==
> U.Generator.Element
- Doug
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