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Calc Kit

Define a calculator once in a small Ruby DSL — typed inputs, outputs, and a calculate method — and Calc Kit gives you validation and a working calculator. Here's the definition on the left and the live calculator on the right.

The definition

class BuildEstimateCalculator < ApplicationCalculator
  input :weeks, :integer, min: 1, default: 6
  input :weekly_rate, :decimal, min: 0, default: 6000
  input :complexity, :select,
    options: %w[simple standard complex]
  input :rush, :boolean, default: false

  output :base, :currency
  output :total, :currency

  def calculate
    base  = weeks * weekly_rate
    total = base * MULTIPLIERS.fetch(complexity)
    total *= 1.2 if rush
    { base:, total: }
  end
end

Calc Kit

The definition

Try it