in reply to Re^3: Small Perl 6 discoveries II, Rats
in thread [Perl6] Small discoveries I, __DATA__

How does one coerce perl6 into displaying the actual numerator and denominator of these rationals?
$x.nude

That would make sense if the numerator and denominator were $x.nu and $x.de, but they're not. You have to type out $x.numerator and $x.denominator. I thought we were trying to make Perl6 safe for 10-year-old girls, but I guess someone just couldn't pass up an opportunity for a crude joke.

  • Comment on Re^4: Small Perl 6 discoveries II, Rats

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Re^5: Small Perl 6 discoveries II, Rats
by syphilis (Archbishop) on Oct 22, 2017 at 11:34 UTC
    $x.nude

    That enables me to see that 1.111111111111111111111.FatRat and 1.111111111111111111111.Rat have equivalent rational values: 
    > my $x = 1.111111111111111111111.Rat; $x.nude
(1111111111111111111111 1000000000000000000000)
> my $y = 1.111111111111111111111.FatRat; $y.nude
(1111111111111111111111 1000000000000000000000)

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    and that $x (the Rat) gets handled in a way that I don't really expect: 
    > my $r1 = $x * 0.3
0.333333333333333
> $r1 = $x * 0.3.Rat
0.333333333333333
> $r1 = $x * 0.3.Num
0.333333333333333
> $r1 = $x * 3e-1
0.333333333333333
> $r1 = $x * 0.3.FatRat
0.3333333333333333333333

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    though the last result is as I expected.
    Compare those outputs with: 
    > my $r2 = $y * 0.3
0.3333333333333333333333
> my $r2 = $y * 0.3.Rat
0.3333333333333333333333
> my $r2 = $y * 0.3.Num
0.333333333333333
> my $r2 = $y * 3e-1
0.333333333333333
> my $r2 = $y * 0.3.FatRat
0.3333333333333333333333

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    which is more in keeping with my expectations.

    I'm sure it all makes sense if you know how to look at it from the appropriate angle.

    Cheers,
    Rob
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      From docs.perl6.org/type/Rat (anons can't post full urls):
      To prevent the numerator and denominator from becoming pathologically large, the denominator is limited to 64 bit storage. On overflow of the denominator a Num (floating-point number) is returned instead.
      However, Rat values generated from decimal notation can violate the 64-bit limit.

      You can use $x.WHAT to find $x's type if you get tired of guessing based on the number of decimal places displayed.

[reply]
        To prevent the numerator and denominator from becoming pathologically large, the denominator is limited to 64 bit storage

        Well, that doesn't seem to be the case with (latest) rakudo-star-2017.07: 
        > my $x=9.999999999999999999999999999999999999999999999.Rat; $x.nude
(9999999999999999999999999999999999999999999999 1000000000000000000000
+000000000000000000000000)
> $x.WHAT
(Rat)

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        but the base 10 denominator of 1000000000000000000000000000000000000000000000 is a 150-bit value.

        The documentation also concludes with "Rat objects are immutable" - yet the following operation converts $x from a Rat to a FatRat: 
        > $x *= 0.3.FatRat; $x.nude
(29999999999999999999999999999999999999999999997 100000000000000000000
+00000000000000000000000000)
> $x.WHAT
(FatRat)

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        Am I misunderstanding that documentation ?
        Is there a way of interpreting the documentation such that it does match the above behaviours ?

        Cheers,
        Rob
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