List::Util::uniqnum() broken in current Scalar-List-Utils

[p5pRT]

Migrated from rt.perl.org#134481 (status was 'open')

Searchable as RT134481$

[p5pRT]

From @sisyphus

The dual-life module Scalar-List-Utils is currently at version 1.52.
It's List​::Util​::uniqnum() function is prone to errors.

The pull request at Dual-Life/Scalar-List-Utils#79
fixes those errors.
It also amends the test script t/uniq.t so that the failures of version
1.52 are exposed. Those amendments to t/uniq.t further serve to verify that
the pull request fixes those failures.
Attached is that amended version of t/uniq.t. Run it using current blead to
see the current failures.

All perl configurations are subject to uniqnum() failures, though not all
configurations fail in exactly the same way.

How should I proceed to have this fixed in time for perl-5.32 ?

Cheers,
Rob

Summary of my perl5 (revision 5 version 31 subversion 4) configuration​:

  Platform​:
  osname=MSWin32
  osvers=6.1.7601
  archname=MSWin32-x64-multi-thread
  uname=''
  config_args='undef'
  hint=recommended
  useposix=true
  d_sigaction=undef
  useithreads=define
  usemultiplicity=define
  use64bitint=define
  use64bitall=undef
  uselongdouble=undef
  usemymalloc=n
  default_inc_excludes_dot=define
  bincompat5005=undef
  Compiler​:
  cc='gcc'
  ccflags =' -s -O2 -DWIN32 -DWIN64 -DCONSERVATIVE
-DPERL_TEXTMODE_SCRIPTS -DPERL_IMPLICIT_CONTEXT -DPERL_IMPLICIT_SYS
-DUSE_PERLIO -D__USE_MINGW_ANSI_STDIO -fwrapv -fno-strict-aliasing
-mms-bitfields'
  optimize='-s -O2'
  cppflags='-DWIN32'
  ccversion=''
  gccversion='8.3.0'
  gccosandvers=''
  intsize=4
  longsize=4
  ptrsize=8
  doublesize=8
  byteorder=12345678
  doublekind=3
  d_longlong=define
  longlongsize=8
  d_longdbl=define
  longdblsize=16
  longdblkind=3
  ivtype='long long'
  ivsize=8
  nvtype='double'
  nvsize=8
  Off_t='long long'
  lseeksize=8
  alignbytes=8
  prototype=define
  Linker and Libraries​:
  ld='g++'
  ldflags ='-s -L"C​:\_64\blead-5.31.4\lib\CORE"
-L"C​:\_64\gcc-straw-830\mingw64\lib"'
  libpth=C​:\_64\gcc-straw-830\mingw64\lib
C​:\_64\gcc-straw-830\mingw64\x86_64-w64-mingw32\lib
C​:\_64\msys_830\1.0\local\lib
C​:\_64\gcc-straw-830\mingw64\lib\gcc\x86_64-w64-mingw32\8.3.0
  libs= -lmoldname -lkernel32 -luser32 -lgdi32 -lwinspool -lcomdlg32
-ladvapi32 -lshell32 -lole32 -loleaut32 -lnetapi32 -luuid -lws2_32 -lmpr
-lwinmm -lversion -lodbc32 -lodbccp32 -lcomctl32
  perllibs= -lmoldname -lkernel32 -luser32 -lgdi32 -lwinspool -lcomdlg32
-ladvapi32 -lshell32 -lole32 -loleaut32 -lnetapi32 -luuid -lws2_32 -lmpr
-lwinmm -lversion -lodbc32 -lodbccp32 -lcomctl32
  libc=
  so=dll
  useshrplib=true
  libperl=libperl531.a
  gnulibc_version=''
  Dynamic Linking​:
  dlsrc=dl_win32.xs
  dlext=dll
  d_dlsymun=undef
  ccdlflags=' '
  cccdlflags=' '
  lddlflags='-mdll -s -L"C​:\_64\blead-5.31.4\lib\CORE"
-L"C​:\_64\gcc-straw-830\mingw64\lib"'

Characteristics of this binary (from libperl)​:
  Compile-time options​:
  HAS_TIMES
  HAVE_INTERP_INTERN
  MULTIPLICITY
  PERLIO_LAYERS
  PERL_COPY_ON_WRITE
  PERL_DONT_CREATE_GVSV
  PERL_IMPLICIT_CONTEXT
  PERL_IMPLICIT_SYS
  PERL_MALLOC_WRAP
  PERL_OP_PARENT
  PERL_PRESERVE_IVUV
  USE_64_BIT_INT
  USE_ITHREADS
  USE_LARGE_FILES
  USE_LOCALE
  USE_LOCALE_COLLATE
  USE_LOCALE_CTYPE
  USE_LOCALE_NUMERIC
  USE_LOCALE_TIME
  USE_PERLIO
  USE_PERL_ATOF
  Built under MSWin32
  Compiled at Sep 21 2019 10​:05​:36
  @​INC​:
  C​:/_64/blead-5.31.4/site/lib
  C​:/_64/blead-5.31.4/lib

[p5pRT]

From @sisyphus

#!./perl

use strict;
use warnings;
use Config; # to determine nvsize
use Test​::More tests => 37;
use List​::Util qw( uniqnum uniqstr uniq );

use Tie​::Array;

is_deeply( [ uniqstr ],
  [],
  'uniqstr of empty list' );

is_deeply( [ uniqstr qw( abc ) ],
  [qw( abc )],
  'uniqstr of singleton list' );

is_deeply( [ uniqstr qw( x x x ) ],
  [qw( x )],
  'uniqstr of repeated-element list' );

is_deeply( [ uniqstr qw( a b a c ) ],
  [qw( a b c )],
  'uniqstr removes subsequent duplicates' );

is_deeply( [ uniqstr qw( 1 1.0 1E0 ) ],
  [qw( 1 1.0 1E0 )],
  'uniqstr compares strings' );

{
  my $warnings = "";
  local $SIG{__WARN__} = sub { $warnings .= join "", @​_ };

  is_deeply( [ uniqstr "", undef ],
  [ "" ],
  'uniqstr considers undef and empty-string equivalent' );

  ok( length $warnings, 'uniqstr on undef yields a warning' );

  is_deeply( [ uniqstr undef ],
  [ "" ],
  'uniqstr on undef coerces to empty-string' );
}

SKIP​: {
  skip 'Perl 5.007003 with utf8​::encode is required', 3 if $] lt "5.007003";
  my $warnings = "";
  local $SIG{__WARN__} = sub { $warnings .= join "", @​_ };

  my $cafe = "cafe\x{301}";

  is_deeply( [ uniqstr $cafe ],
  [ $cafe ],
  'uniqstr is happy with Unicode strings' );

  SKIP​: {
  skip "utf8​::encode not available", 1
  unless defined &utf8​::encode;
  utf8​::encode( my $cafebytes = $cafe );

  is_deeply( [ uniqstr $cafe, $cafebytes ],
  [ $cafe, $cafebytes ],
  'uniqstr does not squash bytewise-equal but differently-encoded strings' );
  }

  is( $warnings, "", 'No warnings are printed when handling Unicode strings' );
}

if($Config{nvsize} == 8 && $Config{ivsize} == 8) {

  is_deeply( [ uniqnum qw( 1 1.0 1E0 2 3 9223372036854775808 9.2233720368547758e+18) ],
  [ 1, 2, 3, 9223372036854775808 ],
  'uniqnum compares numbers' );
}

else {

  is_deeply( [ uniqnum qw( 1 1.0 1E0 2 3 ) ],
  [ 1, 2, 3 ],
  'uniqnum compares numbers' );
}

is_deeply( [ uniqnum qw( 1 1.1 1.2 1.3 ) ],
  [ 1, 1.1, 1.2, 1.3 ],
  'uniqnum distinguishes floats' );

{
  my @​nums = map $_+0.1, 1e7..1e7+5;
  is_deeply( [ uniqnum @​nums ],
  [ @​nums ],
  'uniqnum distinguishes large floats' );

  my @​strings = map "$_", @​nums;
  is_deeply( [ uniqnum @​strings ],
  [ @​strings ],
  'uniqnum distinguishes large floats (stringified)' );
}

my ($uniq_count1, $uniq_count2, $equiv);

if($Config{nvsize} == 8) {
  # NV is either 'double' or 8-byte 'long double'

  # The 2 values should be unequal - but just in case perl is buggy​:
  $equiv = 1 if 1.4142135623730951 == 1.4142135623730954;

  $uniq_count1 = List​::Util​::uniqnum (1.4142135623730951,
  1.4142135623730954 );

  $uniq_count2 = List​::Util​::uniqnum('1.4142135623730951',
  '1.4142135623730954' );
}

elsif(length(sqrt(2)) > 25) {
  # NV is either IEEE 'long double' or '__float128' or doubledouble

  if(1 + (2 ** -1074) != 1) {
  # NV is doubledouble

  # The 2 values should be unequal - but just in case perl is buggy​:
  $equiv = 1 if 1 + (2 ** -1074) == 1 + (2 ** - 1073);

  $uniq_count1 = List​::Util​::uniqnum (1 + (2 ** -1074),
  1 + (2 ** -1073) );
  # The 2 values should be unequal - but just in case perl is buggy​:
  $equiv = 1 if 4.0564819207303340847894502572035e31 == 4.0564819207303340847894502572034e31;

  $uniq_count2 = List​::Util​::uniqnum('4.0564819207303340847894502572035e31',
  '4.0564819207303340847894502572034e31' );
  }

  else {
  # NV is either IEEE 'long double' or '__float128'

  # The 2 values should be unequal - but just in case perl is buggy​:
  $equiv = 1 if 1.7320508075688772935274463415058722 == 1.73205080756887729352744634150587224;

  $uniq_count1 = List​::Util​::uniqnum (1.7320508075688772935274463415058722,
  1.73205080756887729352744634150587224 );

  $uniq_count2 = List​::Util​::uniqnum('1.7320508075688772935274463415058722',
  '1.73205080756887729352744634150587224' );
  }
}

else {
  # NV is extended precision 'long double'

  # The 2 values should be unequal - but just in case perl is buggy​:
  $equiv = 1 if 2.2360679774997896963 == 2.23606797749978969634;

  $uniq_count1 = List​::Util​::uniqnum (2.2360679774997896963,
  2.23606797749978969634 );

  $uniq_count2 = List​::Util​::uniqnum('2.2360679774997896963',
  '2.23606797749978969634' );
}

if($equiv) {
  is($uniq_count1, 1, 'uniqnum preserves uniqness of high precision floats');
  is($uniq_count2, 1, 'uniqnum preserves uniqness of high precision floats (stringified)');
}

else {
  is($uniq_count1, 2, 'uniqnum preserves uniqness of high precision floats');
  is($uniq_count2, 2, 'uniqnum preserves uniqness of high precision floats (stringified)');
}

SKIP​: {
  skip ('test not relevant for this perl configuration', 1) unless $Config{nvsize} == 8
  && $Config{ivsize} == 8;

  my @​in = (~0, ~0 - 1, 18446744073709551614.0, 18014398509481985, 1.8014398509481985e16);
  my(@​correct);

  # On perl-5.6.2 (and perhaps other old versions), ~0 - 1 is assigned to an NV.
  # This affects the outcome of the following test, so we need to first determine
  # whether ~0 - 1 is an NV or a UV​:

  if("$in[1]" eq "1.84467440737096e+19") {

  # It's an NV and $in[2] is a duplicate of $in[1]
  @​correct = (~0, ~0 - 1, 18014398509481985, 1.8014398509481985e16);
  }
  else {

  # No duplicates in @​in
  @​correct = @​in;
  }

  is_deeply( [ uniqnum @​in ],
  [ @​correct ],
  'uniqnum correctly compares UV/IVs that overflow NVs' );
}

# Hard to know for sure what an Inf is going to be. Lets make one
my $Inf = 0 + 1E1000;
my $NaN;
$Inf **= 1000 while ( $NaN = $Inf - $Inf ) == $NaN;

is_deeply( [ uniqnum 0, 1, 12345, $Inf, -$Inf, $NaN, 0, $Inf, $NaN ],
  [ 0, 1, 12345, $Inf, -$Inf, $NaN ],
  'uniqnum preserves the special values of +-Inf and Nan' );

SKIP​: {
  my $maxuint = ~0;
  my $maxint = ~0 >> 1;
  my $minint = -(~0 >> 1) - 1;

  my @​nums = ($maxuint, $maxuint-1, -1, $Inf, $NaN, $maxint, $minint, 1 );

  is_deeply( [ uniqnum @​nums, 1.0 ],
  [ @​nums ],
  'uniqnum preserves uniqness of full integer range' );

  my @​strs = map "$_", @​nums;

  if($maxuint !~ /\A[0-9]+\z/) {
  skip( "Perl $] doesn't stringify UV_MAX right ($maxuint)", 1 );
  }
  elsif($] < 5.022 && $^O =~ /MSWin32/i) {
  skip( "On MS Windows,perl $] stringifies infs and nans into something unusable", 1 );
  }
 

  is_deeply( [ uniqnum @​strs, "1.0" ],
  [ @​strs ],
  'uniqnum preserves uniqness of full integer range (stringified)' );
}

{
  my $warnings = "";
  local $SIG{__WARN__} = sub { $warnings .= join "", @​_ };

  is_deeply( [ uniqnum 0, undef ],
  [ 0 ],
  'uniqnum considers undef and zero equivalent' );

  ok( length $warnings, 'uniqnum on undef yields a warning' );

  is_deeply( [ uniqnum undef ],
  [ 0 ],
  'uniqnum on undef coerces to zero' );
}

is_deeply( [uniqnum 0, -0.0 ],
  [0],
  'uniqnum handles negative zero');

is_deeply( [ uniq () ],
  [],
  'uniq of empty list' );

{
  my $warnings = "";
  local $SIG{__WARN__} = sub { $warnings .= join "", @​_ };

  is_deeply( [ uniq "", undef ],
  [ "", undef ],
  'uniq distintinguishes empty-string from undef' );

  is_deeply( [ uniq undef, undef ],
  [ undef ],
  'uniq considers duplicate undefs as identical' );

  ok( !length $warnings, 'uniq on undef does not warn' );
}

is( scalar( uniqstr qw( a b c d a b e ) ), 5, 'uniqstr() in scalar context' );

{
  package Stringify;

  use overload '""' => sub { return $_[0]->{str} };

  sub new { bless { str => $_[1] }, $_[0] }

  package main;

  my @​strs = map { Stringify->new( $_ ) } qw( foo foo bar );

  is_deeply( [ map "$_", uniqstr @​strs ],
  [ map "$_", $strs[0], $strs[2] ],
  'uniqstr respects stringify overload' );
}

{
  package Numify;

  use overload '0+' => sub { return $_[0]->{num} };

  sub new { bless { num => $_[1] }, $_[0] }

  package main;
  use Scalar​::Util qw( refaddr );

  my @​nums = map { Numify->new( $_ ) } qw( 2 2 5 );

  # is_deeply wants to use eq overloading
  my @​ret = uniqnum @​nums;
  ok( scalar @​ret == 2 &&
  refaddr $ret[0] == refaddr $nums[0] &&
  refaddr $ret[1] == refaddr $nums[2],
  'uniqnum respects numify overload' );
}

{
  package DestroyNotifier;

  use overload '""' => sub { "SAME" };

  sub new { bless { var => $_[1] }, $_[0] }

  sub DESTROY { ${ $_[0]->{var} }++ }

  package main;

  my @​destroyed = (0) x 3;
  my @​notifiers = map { DestroyNotifier->new( \$destroyed[$_] ) } 0 .. 2;

  my @​uniqstr = uniqstr @​notifiers;
  undef @​notifiers;

  is_deeply( \@​destroyed, [ 0, 1, 1 ],
  'values filtered by uniqstr() are destroyed' );

  undef @​uniqstr;
  is_deeply( \@​destroyed, [ 1, 1, 1 ],
  'all values destroyed' );
}

{
  "a a b" =~ m/(.) (.) (.)/;
  is_deeply( [ uniqstr $1, $2, $3 ],
  [qw( a b )],
  'uniqstr handles magic' );

  "1 1 2" =~ m/(.) (.) (.)/;
  is_deeply( [ uniqnum $1, $2, $3 ],
  [ 1, 2 ],
  'uniqnum handles magic' );
}

{
  my @​array;
  tie @​array, 'Tie​::StdArray';
  @​array = (
  ( map { ( 1 .. 10 ) } 0 .. 1 ),
  ( map { ( 'a' .. 'z' ) } 0 .. 1 )
  );

  my @​u = uniq @​array;
  is_deeply(
  \@​u,
  [ 1 .. 10, 'a' .. 'z' ],
  'uniq uniquifies mixed numbers and strings correctly in a tied array'
  );
}

[p5pRT]

From @jkeenan

On Sat, 05 Oct 2019 04​:23​:25 GMT, sisyphus359@​gmail.com wrote​:

The dual-life module Scalar-List-Utils is currently at version 1.52.
It's List​::Util​::uniqnum() function is prone to errors.

The pull request at Dual-Life/Scalar-List-Utils#79
fixes those errors.
It also amends the test script t/uniq.t so that the failures of version
1.52 are exposed. Those amendments to t/uniq.t further serve to verify that
the pull request fixes those failures.
Attached is that amended version of t/uniq.t. Run it using current blead to
see the current failures.

All perl configurations are subject to uniqnum() failures, though not all
configurations fail in exactly the same way.

How should I proceed to have this fixed in time for perl-5.32 ?

Cheers,
Rob

It's unclear from this ticket what the failures in List​::Util​::uniqnum() actually are. Perhaps more to the point, the ticket doesn't make clear *where* they occur. Is this a Windows-specific problem?

Thank you very much.

--
James E Keenan (jkeenan@​cpan.org)

[p5pRT]

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

[p5pRT]

From @sisyphus

On Sat, 05 Oct 2019 05​:03​:46 -0700, jkeenan wrote​:

It's unclear from this ticket what the failures in
List​::Util​::uniqnum() actually are. Perhaps more to the point, the
ticket doesn't make clear *where* they occur. Is this a Windows-
specific problem?

Thank you very much.

It's something that afflicts all systems, and all configurations of perl.

Here's one example of a failure that will appear on all configurations of blead​:

$ perl -MList​::Util="uniqnum" -le '@​x = uniqnum(1.4142135623730951, 1.4142135623730954); print "@​x";'
1.4142135623731

Here uniqnum() is asserting that 1.4142135623730951 and 1.4142135623730954 are the same value, even though perl itself recognizes that the 2 values are distinct​:

$ perl -le 'print "ok" if 1.4142135623730951 != 1.4142135623730954;'
ok

Another failure across all configurations is​:

perl -MList​::Util="uniqnum" -le '@​x = uniqnum(0, -0.0); print "@​x";'
0 0

In this instance, uniqnum() is asserting that 0 and -0.0 are different values.

And here's a third example that afflicts only those perl configurations where both $Config{ivsize} and $Config{nvsize} are 8​:

$ perl -MList​::Util="uniqnum" -le '@​x = uniqnum(9223372036854775808, 9.2233720368547758e+18); print "@​x";'
9223372036854775808 9.22337203685478e+18

Here, uniqnum() asserts that 9223372036854775808 and 9.2233720368547758e+18 are different values even though they are both exact representations of 2 ** 63.

These examples are drawn from the extended version of uniq.t that I attached to my initial bug report.

Cheers,
Rob

[p5pRT]

From @leonerd

On Fri, 04 Oct 2019 21​:23​:25 -0700
"sisyphus \(via RT\)" <perlbug-followup@​perl.org> wrote​:

# New Ticket Created by sisyphus
# Please include the string​: [perl #134481]
# in the subject line of all future correspondence about this issue.
# <URL​: https://rt-archive.perl.org/perl5/Ticket/Display.html?id=134481 >

The dual-life module Scalar-List-Utils is currently at version 1.52.
It's List​::Util​::uniqnum() function is prone to errors.

The pull request at
Dual-Life/Scalar-List-Utils#79 fixes those
errors. It also amends the test script t/uniq.t so that the failures
of version 1.52 are exposed. Those amendments to t/uniq.t further
serve to verify that the pull request fixes those failures.
Attached is that amended version of t/uniq.t. Run it using current
blead to see the current failures.

I've been waiting until you get to the end of adjusting that PR before
I take a look at it, as you seemed to be continuing to work on it.

Is it now ready to merge?

--
Paul "LeoNerd" Evans

leonerd@​leonerd.org.uk | https://metacpan.org/author/PEVANS
http​://www.leonerd.org.uk/ | https://www.tindie.com/stores/leonerd/

[p5pRT]

From @sisyphus

On Sat, 05 Oct 2019 07​:33​:27 -0700, leonerd@​leonerd.org.uk wrote​:

Is it now ready to merge?

Yes, it's now ready.

Cheers,
Rob

[sisyphus]

Since my last post to this thread, we've moved on to
Dual-Life/Scalar-List-Utils#80
which is now, IMO, ready for merging.

Please take a look, and then we can work out how to proceed.

As it stands in perl-5.31.5 and earlier, I think uniqnum() is currently fit for purpose so long as all numbers are either IVs or UVs.
But it is is not fit for purpose when NVs (either integral or fractional values) that cannot be accurately represented in 15 or fewer decimal digits are involved.

For tonight's weird example:
$c = uniqnum(2 ** 50, 1 * (2 ** 50));
will set $c to 2 (unless $Config{ivsize} == 4, which is rare these days).
$c should, of course, be set to 1, as both values are identical.
The error arises partly because the first argument is an NV while the second is an IV, and partly because 2 ** 50 requires more than 15 decimal digits of precision for accurate representation.
Similarly for exponents in the range 51..63, and for a vast number of other integral values.

Cheers,
Rob

[jkeenan]

On 10/22/19 2:42 PM, sisyphus wrote: Since my last post to this thread, we've moved on to Dual-Life/Scalar-List-Utils#80 <Dual-Life/Scalar-List-Utils#80> which is now, IMO, ready for merging. Please take a look, and then we can work out how to proceed. As it stands in perl-5.31.5 and earlier, I think uniqnum() is currently fit for purpose so long as all numbers are either IVs or UVs. But it is is not fit for purpose when NVs (either integral or fractional values) that cannot be accurately represented in 15 or fewer decimal digits are involved. For tonight's weird example: $c = uniqnum(2 ** 50, 1 * (2 ** 50)); will set $c to 2 (unless $Config{ivsize} == 4, which is rare these days). $c should, of course, be set to 1, as both values are identical. The error arises partly because the first argument is an NV while the second is an IV, and partly because 2 ** 50 requires more than 15 decimal digits of precision for accurate representation. Similarly for exponents in the range 51..63, and for a vast number of other integral values. Cheers, Rob

Rob, thank you for your continuing investigations into this. In terms of the Perl 5 core distribution, Scalar-List-Utils is "cpan unstream" at the present time. That means that if you've got code in the Dual Life repository it first needs to be merged into the codebase maintained currently by Paul Evans and he needs to issue a new CPAN version. One of us (perhaps me) will then merge it into Perl 5 blead. Paul attended the Perl 5 Core Summit in Amsterdam this past weekend and we did have some discussion as to whether Scalar-List-Utils should become "p5p upstream" with respect to its maintenance -- in which case it would move to the "dist/" hierarchy within the core distribution. No decision was made on that. Hence, for the meantime you should communicate with the upstream maintainer(s). Thank you very much. Jim Keenan

[toddr]

@leonerd FYI

[sisyphus]

Sorry to raise it again here, but nothing has been done about this. That's ok ... it doesn't have to be fixed immediately. I'm happy so long as it's fixed in 5.32.0. To that end, I'd like to know what I need to do to ensure that it's made a 5.32.0 blocker. Presumably a request for blocker status might be rejected on the basis of "insufficient notice" if one waits too long in the cycle before lodging that request. (And I guess the same request might be forgotten and lost if made too early in the cycle.) Cheers, Rob On Wed, Oct 23, 2019 at 3:57 AM James E Keenan <notifications@github.com> wrote:

…

On 10/22/19 2:42 PM, sisyphus wrote: > Since my last post to this thread, we've moved on to > Dual-Life/Scalar-List-Utils#80 > <Dual-Life/Scalar-List-Utils#80> > which is now, IMO, ready for merging. > > Please take a look, and then we can work out how to proceed. > > As it stands in perl-5.31.5 and earlier, I think uniqnum() is currently > fit for purpose so long as all numbers are either IVs or UVs. > But it is is not fit for purpose when NVs (either integral or fractional > values) that cannot be accurately represented in 15 or fewer decimal > digits are involved. > > For tonight's weird example: > $c = uniqnum(2 ** 50, 1 * (2 ** 50)); > will set $c to 2 (unless $Config{ivsize} == 4, which is rare these days). > $c should, of course, be set to 1, as both values are identical. > The error arises partly because the first argument is an NV while the > second is an IV, and partly because 2 ** 50 requires more than 15 > decimal digits of precision for accurate representation. > Similarly for exponents in the range 51..63, and for a vast number of > other integral values. > > Cheers, > Rob > Rob, thank you for your continuing investigations into this. In terms of the Perl 5 core distribution, Scalar-List-Utils is "cpan unstream" at the present time. That means that if you've got code in the Dual Life repository it first needs to be merged into the codebase maintained currently by Paul Evans and he needs to issue a new CPAN version. One of us (perhaps me) will then merge it into Perl 5 blead. Paul attended the Perl 5 Core Summit in Amsterdam this past weekend and we did have some discussion as to whether Scalar-List-Utils should become "p5p upstream" with respect to its maintenance -- in which case it would move to the "dist/" hierarchy within the core distribution. No decision was made on that. Hence, for the meantime you should communicate with the upstream maintainer(s). Thank you very much. Jim Keenan — You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub <#17174?email_source=notifications&email_token=AAAR3PHSINTCLBSNPAXAQT3QP4WHJA5CNFSM4JDPD3IKYY3PNVWWK3TUL52HS4DFVREXG43VMVBW63LNMVXHJKTDN5WW2ZLOORPWSZGOEB6ORKY#issuecomment-545056939>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AAAR3PH4JIBREWBZNAY7SSDQP4WHJANCNFSM4JDPD3IA> .