pilu/src/Medicine.hs

{-# LANGUAGE NamedFieldPuns #-}
module Medicine (
      Medicine(..)
    , MedicineName
    , Pharmacy
    , pharmacy
  ) where

import CSV (Row(..))
import Data.Map (Map)
import qualified Data.Map as Map (empty, insert, lookup)
import Text.ParserCombinators.Parsec.Error (Message(..))

type MedicineName = String

data Medicine = Medicine {
      name :: MedicineName
    , content :: Float
    , minStock :: Float
  } deriving (Show)

instance Row Medicine where
  fromRow assoc = Medicine <$>
        get "name"
      <*> (read <$> get "content")
      <*> (read <$> get "minStock")
    where
      get key = maybe (Left $ Expect key) Right $ Map.lookup key assoc

type Pharmacy = Map MedicineName Medicine

pharmacy :: [Medicine] -> Pharmacy
pharmacy = foldr (\medicine -> Map.insert (name medicine) medicine) Map.empty