From @zoffixznet

Set operators are a lot less useful with mutable types, like SetHash, because
even when one of the operands is a SetHash, they still return a Set, making
constructs like `∖=` or `∪=` entirely unusable​:

  my $days = SetHash.new​: Date.today … Date.new​: '2014-04-02';
  $days ∖= $days.grep​: *.key.day-of-week > 5;
  dd $days.^name; # "Set"
  $days{Date.today}​:delete; # Cannot call 'DELETE-KEY' on an immutable 'Set'

From @smls

On Mon, 23 Oct 2017 05​:23​:55 -0700, cpan@​zoffix.com wrote​:

Set operators are a lot less useful with mutable types, like SetHash,
because
even when one of the operands is a SetHash, they still return a Set,
making
constructs like `∖=` or `∪=` entirely unusable​:

my $days = SetHash.new​: Date.today … Date.new​: '2014-04-02';
$days ∖= $days.grep​: *.key.day-of-week > 5;
dd $days.^name; # "Set"
$days{Date.today}​:delete; # Cannot call 'DELETE-KEY' on an immutable
'Set'

I don't think setty operators always returning Set, is that different from listy operators/methods (Z, grep, map...) always returning Seq.

For example, when you write​:

  @​foo .= grep​: * %% 2;

Then the grep returns a Seq, and and its the assignment to the Array variable which makes sure that in the end you'll have the results as an Array. (Still the same Array, in fact, just with new contents.)

If you were to use a Scalar variable, you would get essentially the same issue as in your quoted Set example​:

  $foo .= grep​: * %% 2; # Oops, $foo is now an immutable Seq.

The "solution", IMO, would not be to make your quoted example work (by adding further special cases to the return types of the setty operators or otherwise), but rather to make the following variation of it work​:

  my %days is SetHash = Date.today … Date.new​: '2014-04-02';

  %days ∖= %days.grep​: *.key.day-of-week > 5;

  %days{Date.today}​:delete;

...and then promote %-sigiled SetHash variables as the recommended way to store SetHash'es.

It should be possible to make this last example work by implementing `method STORE` for type SetHash, right?

(That it currently doesn't, may well be an oversight rather than a design choice.)

The RT System itself - Status changed from 'new' to 'open'

From @zoffixznet

On Mon, 23 Oct 2017 09​:12​:58 -0700, smls75@​gmail.com wrote​:

On Mon, 23 Oct 2017 05​:23​:55 -0700, cpan@​zoffix.com wrote​:

Set operators are a lot less useful with mutable types, like SetHash,
because
even when one of the operands is a SetHash, they still return a Set,
making
constructs like `∖=` or `∪=` entirely unusable​:

my $days = SetHash.new​: Date.today … Date.new​: '2014-04-02';
$days ∖= $days.grep​: *.key.day-of-week > 5;
dd $days.^name; # "Set"
$days{Date.today}​:delete; # Cannot call 'DELETE-KEY' on an immutable
'Set'

I don't think setty operators always returning Set, is that different
from listy operators/methods (Z, grep, map...) always returning Seq.

For example, when you write​:

@​foo .= grep​: * %% 2;

Then the grep returns a Seq, and and its the assignment to the Array
variable which makes sure that in the end you'll have the results as
an Array. (Still the same Array, in fact, just with new contents.)

If you were to use a Scalar variable, you would get essentially the
same issue as in your quoted Set example​:

$foo .= grep​: * %% 2; # Oops, $foo is now an immutable Seq.

The "solution", IMO, would not be to make your quoted example work (by
adding further special cases to the return types of the setty
operators or otherwise), but rather to make the following variation of
it work​:

my %days is SetHash = Date.today … Date.new​: '2014-04-02';

%days ∖= %days.grep​: *.key.day-of-week > 5;

%days{Date.today}​:delete;

...and then promote %-sigiled SetHash variables as the recommended way
to store SetHash'es.

It should be possible to make this last example work by implementing
`method STORE` for type SetHash, right?

(That it currently doesn't, may well be an oversight rather than a
design choice.)

Thanks for clarifying. Yeah, it looks better if it had a % sigil on it too.

Gonna reject this issue and open a new one on our GitHub tracker[^1] to take it for a spin

[1] https://github.com/rakudo/rakudo/issues

From @zoffixznet

Rejecting 'cause it's a misunderstanding of how things work in OP.

Opened the suggestion for making `%` sigil work in rakudo/rakudo#1203

@zoffixznet - Status changed from 'open' to 'rejected'

From @lizmat

On 24 Oct 2017, at 12​:56, Zoffix Znet via RT <perl6-bugs-followup@​perl.org> wrote​:
On Mon, 23 Oct 2017 09​:12​:58 -0700, smls75@​gmail.com wrote​:

On Mon, 23 Oct 2017 05​:23​:55 -0700, cpan@​zoffix.com wrote​:
The "solution", IMO, would not be to make your quoted example work (by
adding further special cases to the return types of the setty
operators or otherwise), but rather to make the following variation of
it work​:

my %days is SetHash = Date.today … Date.new​: '2014-04-02';

%days ∖= %days.grep​: *.key.day-of-week > 5;

%days{Date.today}​:delete;

...and then promote %-sigiled SetHash variables as the recommended way
to store SetHash'es.

It should be possible to make this last example work by implementing
`method STORE` for type SetHash, right?

(That it currently doesn't, may well be an oversight rather than a
design choice.)

Commit b6a4d5b555520451c5c8a made this possible​:

my %d is SetHash = Date.today .. Date.new("2017-11-30”);
%d .= grep​: *.key.day-of-week > 5;
dd %d;

SetHash.new(Date.new(2017,11,5),Date.new(2017,11,12),Date.new(2017,11,26),Date.new(2017,11,4),Date.new(2017,11,19),Date.new(2017,11,11),Date.new(2017,11,18),Date.new(2017,11,25))

From @AlexDaniel

Does it mean that this now needs tests?

On 2017-10-30 06​:42​:25, elizabeth wrote​:

On 24 Oct 2017, at 12​:56, Zoffix Znet via RT <perl6-bugs-
followup@​perl.org> wrote​:
On Mon, 23 Oct 2017 09​:12​:58 -0700, smls75@​gmail.com wrote​:

On Mon, 23 Oct 2017 05​:23​:55 -0700, cpan@​zoffix.com wrote​:
The "solution", IMO, would not be to make your quoted example work
(by
adding further special cases to the return types of the setty
operators or otherwise), but rather to make the following variation
of
it work​:

my %days is SetHash = Date.today … Date.new​: '2014-04-02';

%days ∖= %days.grep​: *.key.day-of-week > 5;

%days{Date.today}​:delete;

...and then promote %-sigiled SetHash variables as the recommended
way
to store SetHash'es.

It should be possible to make this last example work by implementing
`method STORE` for type SetHash, right?

(That it currently doesn't, may well be an oversight rather than a
design choice.)

Commit b6a4d5b555520451c5c8a made this possible​:

my %d is SetHash = Date.today .. Date.new("2017-11-30”);
%d .= grep​: *.key.day-of-week > 5;
dd %d;

SetHash.new(Date.new(2017,11,5),Date.new(2017,11,12),Date.new(2017,11,26),Date.new(2017,11,4),Date.new(2017,11,19),Date.new(2017,11,11),Date.new(2017,11,18),Date.new(2017,11,25))

@AlexDaniel - Status changed from 'rejected' to 'open'

From @lizmat

Hmmm…. I guess this one does… good point! :-)

On 18 Nov 2017, at 17​:57, Aleks-Daniel Jakimenko-Aleksejev via RT <perl6-bugs-followup@​perl.org> wrote​:

Does it mean that this now needs tests?

On 2017-10-30 06​:42​:25, elizabeth wrote​:

On 24 Oct 2017, at 12​:56, Zoffix Znet via RT <perl6-bugs-
followup@​perl.org> wrote​:
On Mon, 23 Oct 2017 09​:12​:58 -0700, smls75@​gmail.com wrote​:

On Mon, 23 Oct 2017 05​:23​:55 -0700, cpan@​zoffix.com wrote​:
The "solution", IMO, would not be to make your quoted example work
(by
adding further special cases to the return types of the setty
operators or otherwise), but rather to make the following variation
of
it work​:

my %days is SetHash = Date.today … Date.new​: '2014-04-02';

%days ∖= %days.grep​: *.key.day-of-week > 5;

%days{Date.today}​:delete;

...and then promote %-sigiled SetHash variables as the recommended
way
to store SetHash'es.

It should be possible to make this last example work by implementing
`method STORE` for type SetHash, right?

(That it currently doesn't, may well be an oversight rather than a
design choice.)

Commit b6a4d5b555520451c5c8a made this possible​:

my %d is SetHash = Date.today .. Date.new("2017-11-30”);
%d .= grep​: *.key.day-of-week > 5;
dd %d;

SetHash.new(Date.new(2017,11,5),Date.new(2017,11,12),Date.new(2017,11,26),Date.new(2017,11,4),Date.new(2017,11,19),Date.new(2017,11,11),Date.new(2017,11,18),Date.new(2017,11,25))

From @zoffixznet

I see tests already exists for this ticket in S02-types/sethash.t

@zoffixznet - Status changed from 'open' to 'resolved'