my @a; 
push @a, /\.\./ ? do{ my($lo,$hi) = split'\.\.'; $lo..$hi} : $_ 
    for split',', $string; 
print @a;;

##or 

my @a = map{ 
    /\.\./ 
        ? do{ my( $lo,$hi ) = split '\.\.'; $lo .. $hi } 
        : $_ 
} split ',', $string; print @a;;
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