this is my solution so far. it has to loop through all the columns even though only 1 needs to be replaced

#!/usr/bin/perl
use strict;
use warnings;

my $row = {
a => 1,
b => 2,
c => 3,
d => 4
};

my $evalStatement="a>0";

sub evaluateRow { 
   my ($row) = @_;

## loop through each column a,b,c,d and if column exists in the evalua
+tion statement
## replace column with value
   my $evaluateMe = $evalStatement;
  foreach my $colname (keys %$row) {
     my $val = $row->{$colname};
     $evaluateMe =~ s/$colname/$val/g;
  }

  if (eval($evaluateMe)) {
     return 1 ## "ACCEPT row"
  } 
  
  return 0 ## "REMOVE row"
}
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