RobotCost.hs

type Cost = Int

data RobotCost = RobotCost {
  oreCost :: Cost,
  clayCost :: Cost,
  obsidianCost :: Cost
} deriving (Eq, Show)

instance Semigroup RobotCost where
  (<>) rc1 rc2 =
      RobotCost {
        oreCost = oreCost rc1 + oreCost rc2,
        clayCost = clayCost rc1 + clayCost rc2,
        obsidianCost = obsidianCost rc1 + obsidianCost rc2
      }
      
  stimes n rc =
    RobotCost {
      oreCost = oreCost rc * fromIntegral n,
      clayCost = clayCost rc * fromIntegral n,
      obsidianCost = obsidianCost rc * fromIntegral n
    }

instance Monoid RobotCost where
  mempty = RobotCost { oreCost = 0, clayCost = 0, obsidianCost = 0 }
  mappend = (<>)