hi monk I am studying chemistry in the university,
and then I try to write all the things in the textbook with Perl6 or Perl,
like balancing the chemical formula or other process!
Then I encountered the problem is on perl6 custom operator.
I feel I have been repeating my code and myself when i use the feature.
It is hard to read and write, and what is the way to deal with such problems?

#!/usr/bin/env perl6
use v6;
#basic SI(International System of Units) type 


role MetricPrefix {
    method baseOn ( Str $base , Numeric $input ) {
        given $base {
            when 'pico' { return $input * 10**-12 }
            when 'namo' { return $input * 10**-9 }
            when 'micro' { return $input * 10**-6}
            when 'milli' { return $input * 10**-3 }
            when 'centi' { return $input * 10**-2 }
            when 'hecto' { return $input * 10**2 }
            when 'kilo' { return $input * 10**3 }
            when 'mega' { return $input * 10**6 }
            when 'giga' { return $input * 10**9 }
            when 'tera' { return $input * 10**12 }
            default { fail "you must input a metric prefix which allow
+ pico to tera" }
        }
    }
}



class Mass does MetricPrefix {
    #basic Mass is g is different form si statda
    has $.g;

    submethod BUILD ( :$!g  ) {
    }

}

class Length does MetricPrefix {
    has $.Length ;
    
    submethod BUILD ( :$!Length  ) {
    }
}



multi postfix:<(kg)>( $input ) {
    return Mass.new( g => Mass.baseOn("kilo",$input) ) or fail "you Mu
+st input a number";
}

multi postfix:<(g)>( $input ) {
    return Mass.new( g => $input ) or fail "you Must input a number";
}

multi infix:<+>( Mass $inputOne , Mass $inputTwo ) is assoc<right> {
    return Mass.new( g => $inputOne.g + $inputTwo.g) or fail "error in
+ there ";
}

multi infix:<->( Mass $inputOne , Mass $inputTwo ) is assoc<right> {
    return Mass.new( g => $inputOne.g - $inputTwo.g) or fail "error in
+ there ";
}

multi infix:<*>( Mass $inputOne , Mass $inputTwo ) is assoc<right> is 
+tighter( &infix:<+> ) is tighter( &infix:<-> ) is tighter( &infix:</>
+) {
    return Mass.new( g => $inputOne.g * $inputTwo.g) or fail "error in
+ there ";
}

multi infix:</>( Mass $inputOne , Mass $inputTwo ) is assoc<right> is 
+tighter( &infix:<+> ) is tighter( &infix:<-> )  {
    return Mass.new( g => $inputOne.g / $inputTwo.g) or fail "error in
+ there ";
}





#the meterLeng
multi postfix:<(km)>( $input ) {
    return Length.new( Length => Length.baseOn("kilo",$input) ) or fai
+l "you Must input a number";
}

multi postfix:<(m)>( $input ) {
    return Length.new( Length => $input ) or fail "you Must input a nu
+mber";
}

multi infix:<+>( Length $inputOne , Length $inputTwo ) is assoc<right>
+ {
    return Length.new( Length => $inputOne.Length + $inputTwo.Length) 
+or fail "error in there ";
}

multi infix:<->( Length $inputOne , Length $inputTwo ) is assoc<right>
+ {
    return Length.new( Length => $inputOne.Length - $inputTwo.Length) 
+or fail "error in there ";
}

multi infix:<*>( Length $inputOne , Length $inputTwo ) is assoc<right>
+ is tighter( &infix:<+> ) is tighter( &infix:<-> ) is tighter( &infix
+:</>) {
    return Length.new( Length => $inputOne.Length * $inputTwo.Length) 
+or fail "error in there ";
}

multi infix:</>( Length $inputOne , Length $inputTwo ) is assoc<right>
+ is tighter( &infix:<+> ) is tighter( &infix:<-> )  {
    return Length.new( Length => $inputOne.Length / $inputTwo.Length) 
+or fail "error in there ";
}


#just a test
say 10(kg) + 1(g);
say 10(m) + 1(m);
[download]

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