28 lines
617 B
Perl
28 lines
617 B
Perl
# 20200704 added Perl programming solution
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package Writer;
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use strict;
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use warnings;
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sub new {
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my ($class, $value, $log) = @_;
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return bless [ $value => $log ], $class;
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}
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sub Bind {
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my ($self, $code) = @_;
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my ($value, $log) = @$self;
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my $n = $code->($value);
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return Writer->new( @$n[0], $log.@$n[1] );
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}
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sub Unit { Writer->new($_[0], sprintf("%-17s: %.12f\n",$_[1],$_[0])) }
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sub root { Unit sqrt($_[0]), "Took square root" }
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sub addOne { Unit $_[0]+1, "Added one" }
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sub half { Unit $_[0]/2, "Divided by two" }
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print Unit(5, "Initial value")->Bind(\&root)->Bind(\&addOne)->Bind(\&half)->[1];
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