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Re: Set difference using hashes vs array

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From:
Norman Gaywood
Date:
November 23, 2017 05:20
Subject:
Re: Set difference using hashes vs array
Message ID:
CAHJ-_U5Vh=RzFex-n1hf2ezj7-C5vEv1ADWokPCx+DTuAU=d1g@mail.gmail.com
For compactness, here are the 1-liners:

$ perl6
To exit type 'exit' or '^D'
> my %a= k=>"k", e=>"e", r=>"r"; my %r= r=>"r"; my %e= e=>"e"; my Set $s =
%a (-) %r (-) %e;
Cannot convert string to number: base-10 number must begin with valid
digits or '.' in '⏏k' (indicated by ⏏)
  in block <unit> at <unknown file> line 1

> my %a= k=>"k", e=>"e", r=>"r"; my %r= r=>"r"; my %e= e=>"e"; my Set $s =
(%a (-) %r) (-) %e;
set(k)
> my @a= "k", "e", "r"; my @r= "r"; my @e= "e"; my Set $s = @a (-) @r (-)
@e;
set(k)
>


On 23 November 2017 at 15:41, Norman Gaywood <ngaywood@une.edu.au> wrote:

> I'm not sure what this error message means and what is going on here:
> perl6 --version
> This is Rakudo version 2017.08 built on MoarVM version 2017.08.1
> implementing Perl 6.c.
>
> $ cat tt-h.p6
> #!/usr/bin/env perl6
>
> my %excludes = "exclude" => "exclude";
> my %all = :keep("keep"), :exclude("exclude"), :remove("remove");
> my %remove = :remove("remove");
>
> my Set $take1 = (%all (-) %remove) (-) %excludes;
> dd $take1;
> my Set $take2 = %all (-) %remove (-) %excludes;
> dd $take2;
>
> $ ./tt-h.p6
> Set $take1 = set("keep")
> Cannot convert string to number: base-10 number must begin with valid
> digits or '.' in '⏏remove' (indicated by ⏏)
>   in block <unit> at ./tt-h.p6 line 10
>
> The difference in $take1 and $take2 are the brackets around the 1st set
> operation.
>
> If I use arrays then no problem with either expression:
>
> $ cat tt-a.p6
> #!/usr/bin/env perl6
>
> my @excludes = "exclude";
> my @all = "keep", "exclude", "remove";
> my @remove = "remove";
>
> my Set $take1 = (@all (-) @remove) (-) @excludes;
> dd $take1;
> my Set $take2 = @all (-) @remove (-) @excludes;
> dd $take2;
>
> $ ./tt-a.p6
> Set $take1 = set("keep")
> Set $take2 = set("keep")
>
> --
> Norman Gaywood, Computer Systems Officer
> School of Science and Technology
> University of New England
> Armidale NSW 2351, Australia
>
> ngaywood@une.edu.au  http://turing.une.edu.au/~ngaywood
> Phone: +61 (0)2 6773 2412 <(02)%206773%202412>  Mobile: +61 (0)4 7862 0062
>
> Please avoid sending me Word or Power Point attachments.
> See http://www.gnu.org/philosophy/no-word-attachments.html
>



-- 
Norman Gaywood, Computer Systems Officer
School of Science and Technology
University of New England
Armidale NSW 2351, Australia

ngaywood@une.edu.au  http://turing.une.edu.au/~ngaywood
Phone: +61 (0)2 6773 2412  Mobile: +61 (0)4 7862 0062

Please avoid sending me Word or Power Point attachments.
See http://www.gnu.org/philosophy/no-word-attachments.html

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