praxis

Various programming exercises.
git clone git://git.jtobin.io/praxis.git
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Main.hs (785B)

      1 
      2 module Main where
      3 
      4 import Currency
      5 import Data.Scientific
      6 import Options.Applicative
      7 import Options.Applicative.Types
      8 
      9 main :: IO ()
     10 main = execParser parserOptions >>= runProgram
     11 
     12 data ExchangeOptions = ExchangeOptions Scientific String String
     13 
     14 -- | Options parser options.
     15 parserOptions :: ParserInfo ExchangeOptions
     16 parserOptions = info (helper <*> opts) fullDesc where
     17   opts =
     18         ExchangeOptions
     19     <$> argument parseSci (metavar "AMOUNT")
     20     <*> argument str (metavar "CURRENCY")
     21     <*> argument str (metavar "CURRENCY")
     22 
     23 runProgram :: ExchangeOptions -> IO ()
     24 runProgram (ExchangeOptions d x y) = do
     25   val <- query d x y
     26   putStrLn $ show d <> "@" <> x <> "/" <> y <> ": " <> show val
     27 
     28 parseSci :: ReadM Scientific
     29 parseSci = do
     30   sci <- readerAsk
     31   return $ read sci
     32