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type Author=(String,[String])
type Titel=(String,String)
type Publisher=(String,String)
type Year=(String,Int)
type Price=(String,Float)
type Booklist=[(Author,Titel,Publisher,Year,Price)]

exampleList::Booklist
exampleList=new_entry (new_entry [] book) book2

book::(Author,Titel,Publisher,Year,Price)
book=(("author",[("Simon Thomson"),("tufftuff")]),("titel","The craft of functional Programming"),("publisher","Addison-Wesley"),("year",1999),("price",39.95)) 

book2::(Author,Titel,Publisher,Year,Price)
book2=(("author",[("Dan Gookin")]),("titel","Haskell für Dummies"),("publisher","MitP"),("year",1998),("price",99.99))

new_entry::Booklist->(Author,Titel,Publisher,Year,Price)->Booklist
new_entry list ((author,a),(titel,t),(publisher,pub),(year,y),(price,pr)) =[(("author",a),("titel",t),("publisher",pub),("year",y),("price",pr))]++list

searchTitel::Booklist->String->[String]
searchTitel eList s=[(t)|((author,a),(titel,t),(publisher,pub),(year,y),(price,pr))<-eList,substr s t]

substr :: String -> String -> Bool
substr [] _ = True
substr (_:_) [] = False
substr (x:xs) (y:ys) = substr (x:xs) ys || f_substr (x:xs) (y:ys)
  where
    f_substr [] _ = True
    f_substr (_:_) [] = False
    f_substr (x:xs) (y:ys) = (x==y) && f_substr xs ys

allAuthors :: Booklist->[Author]
allAuthors eList=[(a,author)|((a,author),(t,titel),(p,publisher),(y,year),(pr,price))<-eList]
  
num_List::Booklist->[(Int,Titel)]
num_List eList= zip [1..length titels] titels
  where titels=[(titel)|(author,titel,publisher,year,price)<-eList]


--search_book::Booklist->String->(Author,Titel,Publisher,Year,Price)
--search_book eList t=[((a,author),(ti,titel),(p,publisher),(y,year),(pr,price))|((a,author),(ti,titel),(p,publisher),(y,year),(pr, price))<-eList,substr t titel]

show_s::[(String)]->IO()   
show_s x = sequence_(map putStrLn (x))

show_book::(Author,Titel,Publisher,Year,Price)-> IO()
show_book ((author,a),(titel,t),(publisher,pub),(year,y),(price,pr))=show_s x
                                                                     where x=(a++s)
                                                                           s=t:pub:( show y):(show pr):[]