recipe-cost/cout-recette.hs

#! /usr/bin/env runhaskell

data Ingredient = Ingredient { ingredientName :: String
                             , unit_cost :: Double
                             }deriving (Show)

data UsedIngredient = UsedIngredient { ingredient :: Ingredient, quantityUsed :: Double }deriving (Show)

data Recipe = Recipe { recipeName :: String
                     , billOfMaterial :: [ UsedIngredient ]
                     , finalQuantity :: Double
                     , useNumber :: Double
                     }deriving (Show)

recipeCost :: Recipe -> Double
recipeCost (Recipe _ bom _ _) = sum . map ingredientCost $ bom

ingredientCost :: UsedIngredient -> Double
ingredientCost (UsedIngredient (Ingredient _ uCost) qtt) = uCost * qtt

unitCost :: Recipe -> Double -> Double
unitCost (Recipe _ _ qtt _) totalCost = totalCost / qtt

useCost :: Recipe -> Double -> Double
useCost (Recipe _ _ _ uses) totalCost = totalCost / uses

(→) :: Ingredient -> Double -> UsedIngredient
(→) ingredient qtt = UsedIngredient ingredient qtt

eau = Ingredient "Eau" 0.003
savonMarseille = Ingredient "Savon de Marseille" 3.36
bicarbonate = Ingredient "Bicarbonate de soude" 3.81
vinaigreBlanc = Ingredient "Vinaigre blanc" 0.36

lessive :: Recipe
lessive = Recipe "Lessive"
                 [ eau → 2.5
                 , savonMarseille → 0.1
                 , bicarbonate → 0.016
                 , vinaigreBlanc → 0.03
                 ]
                 2.5
                 30

main = do
    putStrLn "Calcul du coût des recettes\n"
    putStrLn "* Lessive :"
    print lessive
    let lessiveTotalCost = recipeCost lessive
        lessiveUnitCost = unitCost lessive lessiveTotalCost
        lessiveUseCost = useCost lessive lessiveTotalCost
    putStrLn $ "  * Prix Total = " ++ show lessiveTotalCost ++ "€"
    putStrLn $ "  * Prix au litre = " ++ show lessiveUnitCost ++ "€"
    putStrLn $ "  * Prix par utilisation = " ++ show lessiveUseCost ++ "€"