Revisiting SE-0132 Rationalizing Sequence end-operation names

Evolution Discussion
1

During the Swift 3 cycle, I proposed SE-0132, "Rationalizing Sequence end-operation names". It was rejected because it needed revision and there was no time to do so. Since then, part of the proposal—partial ranges and the `RangeExpression` slicing protocol—has been adopted in SE-0172, "One-sided Ranges". I''d like to reopen discussion of the rest of the proposal.

To refresh your memory, SE-0132 proposed systematically renaming a number of `Sequence` and `Collection` methods which operate on the beginning and end of a sequence. Many of these methods have names borrowed directly from functional programming; they use terminology in conflicting ways and don't follow our conventions for non-mutating method names. For example, consider the inconsistent and API Guideline-violating names of a few members which operate on the beginning of a sequence or collection:

  first dropFirst() removeFirst()
  prefix(_:) dropFirst(_:) removeFirst(_:)
  prefix(while:) drop(while:) —

These members could be renamed to form consistent "families" where a given term always meant the same thing:

  first removingFirst() removeFirst()
  prefix(_:) removingPrefix(_:) removePrefix(_:)
  prefix(while:) removingPrefix(while:) —

The main question in my mind about this plan is source stability. Back during Swift 3, we broke compatibility willy-nilly, but today we're being a little more circumspect. I believe these names meet the criteria of being actively harmful—they are difficult to discover, so developers don't use these members even when they should, and many of them sound like mutating methods or are unclear about their purpose—but that still doesn't tell us how we should treat the old names.

Basically, when should we introduce the new names?

  1. Swift 4.1 (or whatever pre-Swift 5 version the proposal ends up landing in)
  2. Swift 4.n (the version of Swift 5's compatibility mode for Swift 4)
  3. Swift 5

And when should we deprecate the old ones?

  1. Swift 4.1
  2. Swift 4.n
  3. Swift 5
  4. Swift 6
  5. Never

I'm also open to discussion about whether this should be done at all, whether any additional methods should be included (or included methods should be left alone), whether the now-obsolete `prefix(from:)` `prefix(upTo:)`, and `prefix(through:)` methods should be left alone, deprecated, or removed, and whether this should be done in this proposal or a different one.

The original proposal, which lists all affected methods and explains the logic behind them, is available at <https://github.com/apple/swift-evolution/blob/master/proposals/0132-sequence-end-ops.md&gt;\. Keep in mind that the parts about ranges have already been incorporated into Swift in a revised form, so you can ignore them.

I'll get cracking on an implementation once we figure out what I should implement.

Thanks!

···

--
Brent Royal-Gordon
Architechies

1 Like
2

During the Swift 3 cycle, I proposed SE-0132, "Rationalizing Sequence
end-operation names". It was rejected because it needed revision and there
was no time to do so. Since then, part of the proposal—partial ranges and
the `RangeExpression` slicing protocol—has been adopted in SE-0172,
"One-sided Ranges". I''d like to reopen discussion of the rest of the
proposal.

To refresh your memory, SE-0132 proposed systematically renaming a number
of `Sequence` and `Collection` methods which operate on the beginning and
end of a sequence. Many of these methods have names borrowed directly from
functional programming; they use terminology in conflicting ways and don't
follow our conventions for non-mutating method names. For example, consider
the inconsistent and API Guideline-violating names of a few members which
operate on the beginning of a sequence or collection:

        first dropFirst()
removeFirst()
        prefix(_:) dropFirst(_:)
removeFirst(_:)
        prefix(while:) drop(while:) —

These members could be renamed to form consistent "families" where a given
term always meant the same thing:

        first removingFirst() removeFirst()
        prefix(_:) removingPrefix(_:)
removePrefix(_:)
        prefix(while:) removingPrefix(while:) —

The main question in my mind about this plan is source stability. Back
during Swift 3, we broke compatibility willy-nilly, but today we're being a
little more circumspect. I believe these names meet the criteria of being
actively harmful—they are difficult to discover, so developers don't use
these members even when they should, and many of them sound like mutating
methods or are unclear about their purpose—but that still doesn't tell us
how we should treat the old names.

Basically, when should we introduce the new names?

        1. Swift 4.1 (or whatever pre-Swift 5 version the proposal ends up
landing in)
        2. Swift 4.n (the version of Swift 5's compatibility mode for
Swift 4)
        3. Swift 5

(All of the following IMHO:)

Swift 4.1 or whatever is closest. The new names are very clear, and their
introduction doesn't impair backwards compatibility.

And when should we deprecate the old ones?

        1. Swift 4.1
        2. Swift 4.n
        3. Swift 5
        4. Swift 6
        5. Never

Deprecation warnings: Swift 5. Code continues to compile, and fix-its and a
migrator can get rid of the warning.
Removal of deprecated API: Swift 6; ABI stability may require these symbols
to continue to exist though.

I'm also open to discussion about whether this should be done at all,

whether any additional methods should be included (or included methods
should be left alone), whether the now-obsolete `prefix(from:)`
`prefix(upTo:)`, and `prefix(through:)` methods should be left alone,
deprecated, or removed, and whether this should be done in this proposal or
a different one.

Could deprecate in Swift 5--don't feel strongly about this one. Definitely
a separate proposal.

···

On Thu, Nov 2, 2017 at 7:26 PM, Brent Royal-Gordon via swift-evolution < swift-evolution@swift.org> wrote:

The original proposal, which lists all affected methods and explains the
logic behind them, is available at <Apple · GitHub
swift-evolution/blob/master/proposals/0132-sequence-end-ops.md>. Keep in
mind that the parts about ranges have already been incorporated into Swift
in a revised form, so you can ignore them.

I'll get cracking on an implementation once we figure out what I should
implement.

Thanks!

3

Huge +1. Every time I work with collections, I read the type signatures to be 100% on whether a method will mutate in place or not. I don’t trust the names as they’re not consistent.

R+

···

Sent from my iPhone

On 3 Nov 2017, at 02:58, Xiaodi Wu via swift-evolution <swift-evolution@swift.org> wrote:

On Thu, Nov 2, 2017 at 7:26 PM, Brent Royal-Gordon via swift-evolution <swift-evolution@swift.org> wrote:
During the Swift 3 cycle, I proposed SE-0132, "Rationalizing Sequence end-operation names". It was rejected because it needed revision and there was no time to do so. Since then, part of the proposal—partial ranges and the `RangeExpression` slicing protocol—has been adopted in SE-0172, "One-sided Ranges". I''d like to reopen discussion of the rest of the proposal.

To refresh your memory, SE-0132 proposed systematically renaming a number of `Sequence` and `Collection` methods which operate on the beginning and end of a sequence. Many of these methods have names borrowed directly from functional programming; they use terminology in conflicting ways and don't follow our conventions for non-mutating method names. For example, consider the inconsistent and API Guideline-violating names of a few members which operate on the beginning of a sequence or collection:

        first dropFirst() removeFirst()
        prefix(_:) dropFirst(_:) removeFirst(_:)
        prefix(while:) drop(while:) —

These members could be renamed to form consistent "families" where a given term always meant the same thing:

        first removingFirst() removeFirst()
        prefix(_:) removingPrefix(_:) removePrefix(_:)
        prefix(while:) removingPrefix(while:) —

The main question in my mind about this plan is source stability. Back during Swift 3, we broke compatibility willy-nilly, but today we're being a little more circumspect. I believe these names meet the criteria of being actively harmful—they are difficult to discover, so developers don't use these members even when they should, and many of them sound like mutating methods or are unclear about their purpose—but that still doesn't tell us how we should treat the old names.

Basically, when should we introduce the new names?

        1. Swift 4.1 (or whatever pre-Swift 5 version the proposal ends up landing in)
        2. Swift 4.n (the version of Swift 5's compatibility mode for Swift 4)
        3. Swift 5

(All of the following IMHO:)

Swift 4.1 or whatever is closest. The new names are very clear, and their introduction doesn't impair backwards compatibility.

And when should we deprecate the old ones?

        1. Swift 4.1
        2. Swift 4.n
        3. Swift 5
        4. Swift 6
        5. Never

Deprecation warnings: Swift 5. Code continues to compile, and fix-its and a migrator can get rid of the warning.
Removal of deprecated API: Swift 6; ABI stability may require these symbols to continue to exist though.

I'm also open to discussion about whether this should be done at all, whether any additional methods should be included (or included methods should be left alone), whether the now-obsolete `prefix(from:)` `prefix(upTo:)`, and `prefix(through:)` methods should be left alone, deprecated, or removed, and whether this should be done in this proposal or a different one.

Could deprecate in Swift 5--don't feel strongly about this one. Definitely a separate proposal.

The original proposal, which lists all affected methods and explains the logic behind them, is available at <https://github.com/apple/swift-evolution/blob/master/proposals/0132-sequence-end-ops.md&gt;\. Keep in mind that the parts about ranges have already been incorporated into Swift in a revised form, so you can ignore them.

I'll get cracking on an implementation once we figure out what I should implement.

Thanks!

_______________________________________________
swift-evolution mailing list
swift-evolution@swift.org
https://lists.swift.org/mailman/listinfo/swift-evolution

4

I second Xiaodi. The new names are much improved. Land them in 4.1 or as soon as possible. Depreciations in 5 and removal in 6, though stability may not allow removal.

···

On Nov 2, 2017, at 9:58 PM, Xiaodi Wu via swift-evolution <swift-evolution@swift.org> wrote:

On Thu, Nov 2, 2017 at 7:26 PM, Brent Royal-Gordon via swift-evolution <swift-evolution@swift.org> wrote:
During the Swift 3 cycle, I proposed SE-0132, "Rationalizing Sequence end-operation names". It was rejected because it needed revision and there was no time to do so. Since then, part of the proposal—partial ranges and the `RangeExpression` slicing protocol—has been adopted in SE-0172, "One-sided Ranges". I''d like to reopen discussion of the rest of the proposal.

To refresh your memory, SE-0132 proposed systematically renaming a number of `Sequence` and `Collection` methods which operate on the beginning and end of a sequence. Many of these methods have names borrowed directly from functional programming; they use terminology in conflicting ways and don't follow our conventions for non-mutating method names. For example, consider the inconsistent and API Guideline-violating names of a few members which operate on the beginning of a sequence or collection:

        first dropFirst() removeFirst()
        prefix(_:) dropFirst(_:) removeFirst(_:)
        prefix(while:) drop(while:) —

These members could be renamed to form consistent "families" where a given term always meant the same thing:

        first removingFirst() removeFirst()
        prefix(_:) removingPrefix(_:) removePrefix(_:)
        prefix(while:) removingPrefix(while:) —

The main question in my mind about this plan is source stability. Back during Swift 3, we broke compatibility willy-nilly, but today we're being a little more circumspect. I believe these names meet the criteria of being actively harmful—they are difficult to discover, so developers don't use these members even when they should, and many of them sound like mutating methods or are unclear about their purpose—but that still doesn't tell us how we should treat the old names.

Basically, when should we introduce the new names?

        1. Swift 4.1 (or whatever pre-Swift 5 version the proposal ends up landing in)
        2. Swift 4.n (the version of Swift 5's compatibility mode for Swift 4)
        3. Swift 5

(All of the following IMHO:)

Swift 4.1 or whatever is closest. The new names are very clear, and their introduction doesn't impair backwards compatibility.

And when should we deprecate the old ones?

        1. Swift 4.1
        2. Swift 4.n
        3. Swift 5
        4. Swift 6
        5. Never

Deprecation warnings: Swift 5. Code continues to compile, and fix-its and a migrator can get rid of the warning.
Removal of deprecated API: Swift 6; ABI stability may require these symbols to continue to exist though.

I'm also open to discussion about whether this should be done at all, whether any additional methods should be included (or included methods should be left alone), whether the now-obsolete `prefix(from:)` `prefix(upTo:)`, and `prefix(through:)` methods should be left alone, deprecated, or removed, and whether this should be done in this proposal or a different one.

Could deprecate in Swift 5--don't feel strongly about this one. Definitely a separate proposal.

The original proposal, which lists all affected methods and explains the logic behind them, is available at <https://github.com/apple/swift-evolution/blob/master/proposals/0132-sequence-end-ops.md&gt;\. Keep in mind that the parts about ranges have already been incorporated into Swift in a revised form, so you can ignore them.

I'll get cracking on an implementation once we figure out what I should implement.

Thanks!

_______________________________________________
swift-evolution mailing list
swift-evolution@swift.org
https://lists.swift.org/mailman/listinfo/swift-evolution

5

+1 here, this irked me for a while as well.

···

On Mon, Nov 6, 2017 at 10:05 AM, Rudolf Adamkovič via swift-evolution < swift-evolution@swift.org> wrote:

Huge +1. Every time I work with collections, I read the type signatures to
be 100% on whether a method will mutate in place or not. I don’t trust the
names as they’re not consistent.

R+

Sent from my iPhone

On 3 Nov 2017, at 02:58, Xiaodi Wu via swift-evolution < > swift-evolution@swift.org> wrote:

On Thu, Nov 2, 2017 at 7:26 PM, Brent Royal-Gordon via swift-evolution < > swift-evolution@swift.org> wrote:

During the Swift 3 cycle, I proposed SE-0132, "Rationalizing Sequence
end-operation names". It was rejected because it needed revision and there
was no time to do so. Since then, part of the proposal—partial ranges and
the `RangeExpression` slicing protocol—has been adopted in SE-0172,
"One-sided Ranges". I''d like to reopen discussion of the rest of the
proposal.

To refresh your memory, SE-0132 proposed systematically renaming a number
of `Sequence` and `Collection` methods which operate on the beginning and
end of a sequence. Many of these methods have names borrowed directly from
functional programming; they use terminology in conflicting ways and don't
follow our conventions for non-mutating method names. For example, consider
the inconsistent and API Guideline-violating names of a few members which
operate on the beginning of a sequence or collection:

        first dropFirst()
removeFirst()
        prefix(_:) dropFirst(_:)
removeFirst(_:)
        prefix(while:) drop(while:) —

These members could be renamed to form consistent "families" where a
given term always meant the same thing:

        first removingFirst() removeFirst()
        prefix(_:) removingPrefix(_:)
removePrefix(_:)
        prefix(while:) removingPrefix(while:) —

The main question in my mind about this plan is source stability. Back
during Swift 3, we broke compatibility willy-nilly, but today we're being a
little more circumspect. I believe these names meet the criteria of being
actively harmful—they are difficult to discover, so developers don't use
these members even when they should, and many of them sound like mutating
methods or are unclear about their purpose—but that still doesn't tell us
how we should treat the old names.

Basically, when should we introduce the new names?

        1. Swift 4.1 (or whatever pre-Swift 5 version the proposal ends
up landing in)
        2. Swift 4.n (the version of Swift 5's compatibility mode for
Swift 4)
        3. Swift 5

(All of the following IMHO:)

Swift 4.1 or whatever is closest. The new names are very clear, and their
introduction doesn't impair backwards compatibility.

And when should we deprecate the old ones?

        1. Swift 4.1
        2. Swift 4.n
        3. Swift 5
        4. Swift 6
        5. Never

Deprecation warnings: Swift 5. Code continues to compile, and fix-its and
a migrator can get rid of the warning.
Removal of deprecated API: Swift 6; ABI stability may require these
symbols to continue to exist though.

I'm also open to discussion about whether this should be done at all,

whether any additional methods should be included (or included methods
should be left alone), whether the now-obsolete `prefix(from:)`
`prefix(upTo:)`, and `prefix(through:)` methods should be left alone,
deprecated, or removed, and whether this should be done in this proposal or
a different one.

Could deprecate in Swift 5--don't feel strongly about this one. Definitely
a separate proposal.

The original proposal, which lists all affected methods and explains the
logic behind them, is available at <https://github.com/apple/swif
t-evolution/blob/master/proposals/0132-sequence-end-ops.md>. Keep in
mind that the parts about ranges have already been incorporated into Swift
in a revised form, so you can ignore them.

I'll get cracking on an implementation once we figure out what I should
implement.

Thanks!

_______________________________________________
swift-evolution mailing list
swift-evolution@swift.org
https://lists.swift.org/mailman/listinfo/swift-evolution

_______________________________________________
swift-evolution mailing list
swift-evolution@swift.org
https://lists.swift.org/mailman/listinfo/swift-evolution

6

It's sad to see this not tackled before Swift 5 and the ABI freezing...

A lot of proposals have shown how much naming and consistency are an important goal for swift.

There is a lot of positive feedback from the community on this one.

6 Likes
7

@mackoj This proposal was rejected by the core team.