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  1. {-# LANGUAGE OverloadedStrings #-}
  2. module MyBooks where
  3.  
  4. import qualified Data.Text.Lazy as T
  5. import qualified Data.Time.Calendar as C
  6.  
  7.  
  8. data Publisher = OReilly
  9.                | Manning
  10.                | Pragmatic_Bookshelf
  11.                | Apress
  12.                | Packt_Pub
  13.                | Leanpub
  14.                | Ohm_sha
  15.                | Tatsujin
  16.                | OReilly_JP
  17.                | Gihyo
  18.                deriving(Show, Eq, Ord)
  19.  
  20. data BookCat a = Algorithms a
  21.                | Language a
  22.                | DataScience a
  23.                | Math a
  24.                | Science
  25.                | Other a
  26.                deriving(Show, Eq)
  27.  
  28. data BookInfo = BookInfo {title                 :: T.Text
  29.                           , author              :: Maybe T.Text
  30.                           , publisher           :: Maybe Publisher
  31.                           , bookCats            :: Maybe [BookCat T.Text]
  32.                           , downloadedVersion   :: Maybe T.Text
  33.                           , downloadedDate      :: Maybe C.Day
  34.                         } deriving (Show, Eq)
  35. defaultBookInfo :: BookInfo
  36. defaultBookInfo = BookInfo{title            = ""
  37.                         , author            = Nothing
  38.                         , publisher         = Nothing
  39.                         , bookCats          = Nothing
  40.                         , downloadedVersion = Nothing
  41.                         , downloadedDate    = Nothing
  42.                          }
  43.  
  44.  
  45. myBook = defaultBookInfo {title = "Java8", author = Just "java"}
  46.  
  47. main = print myBook
  48.  
  49.  
  50.  
  51.  
Compilation error #stdin compilation error #stdout 0s 0KB
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stdin
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Standard input is empty
compilation info 
prog.hs:4:18:
    Could not find module `Data.Text.Lazy'
    Perhaps you meant
      Data.Map.Lazy (from containers-0.5.0.0)
      Data.STRef.Lazy (from base)
    Use -v to see a list of the files searched for.
stdout
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Standard output is empty
https://ideone.com/D6FlcS
language:
Haskell (ghc 8.4.4)
created:
9 years ago
visibility:
public

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