Discussion on: Immutibilty

// This is ambiguous, lazy, and the worst form of mutation.
// Its a terrible way to program in any language!
// Its what was done in "c" 40 years ago
// 93 characters

let d = b * b;
d -= 4 * a * c;
if (d < 0) return [];
d = Math.sqrt(d);

// A better way to program.
// Totally non-ambiguous, non lazy, self commenting. 
// No concern for mutability here.
// 193 characters

let taxmultiplier = taxbase*taxbase;
let exciseTax = 4;
let figuretax = taxmultiplier -(exciseTax*stateTax*countytax);
if(figuretax<0) return [];
let taxRoot = Math.sqrt(taxMultipier);

// even better, we have a tax rule a object which, for safety must be immutable; 
// unless the new taxable rates arrive of which we handle separately somewhere
// 138 characters

let a = {taxbase:.04, taxmultipler:'*2', stateTax:.1, countyTax:.05} 
return a.taxmultiplier -(a.exciseTax*a.stateTax*a.countytax);


// This allows us to pass in an object and return a number based on object content.
// 66 characters

function calcTax(a){
 return a.taxmultiplier -(a.exciseTax*a.stateTax*a.countytax);
}

// implementing a decorator
// 72 chars

function calcFloodTax(a){
 let floodtax = .005;
 let tax = calcTax(a);
 return tax * floodtax;
}

// a decorator with injected floodtax
// Total characters 32

function calcFloodTax(a, floodtax){
  return calcTax(a) * floodtax;
}