*Main> :t elem
elem :: (Foldable t, Eq a) => a -> t a -> Bool
*Main> parse "abc" (noneOf ";,.")
*Main> parse "abc" (noneOf ";,.")
Just ('a',"bc")
*Main> parse "abc" (noneOf ";,.a")
Nothing
*Main> parse "aaaaaaaaaaaaaabbbbbb" (many $ char 'a')
Just ("aaaaaaaaaaaaaa","bbbbbb")
*Main> parse "aaaaaaaaaaaaaabbbbbb" (many $ char 'b')
Just ("","aaaaaaaaaaaaaabbbbbb")
*Main> parse "aaaaaaaaaaaaaabbbbbb" (many1 $ char 'b')
Nothing
*Main> parse "aaaaaaaaaaaaaabbbbbb" (many1 $ char 'a')
Just ("aaaaaaaaaaaaaa","bbbbbb")
*Main> parse "" (many $ char 'a')
Just ("","")
*Main> parse "" (many1 $ char 'a')
Nothing
*Main> parse "a,b,c" (char 'a' `sepby` char ',')
Just ("a",",b,c")
*Main> parse "a,a,b,c" (char "abc" `sepby` char ',')
Just ("aa",",b,c")
*Main> parse "a,a,b,c" (char "abc" `sepby` char ',')

*Main> parse "a,a,b,c" (string "abc" `sepby` char ',')
Just ([],"a,a,b,c")
*Main> parse "abc,abc,b,c" (string "abc" `sepby` char ',')
Just (["abc","abc"],",b,c")
*Main> parse "ab,b,c" (string "abc" `sepby1` char ',')
Nothing
*Main> parse "ab,b,c" (string "abc" `sepby` char ',')
Just ([],"ab,b,c")
*Main> :r
[1 of 1] Compiling Main             ( lec14.hs, interpreted )

lec14.hs:130:17: error:
    • Couldn't match type ‘()’ with ‘Char’
      Expected type: Parser Char
        Actual type: Parser ()
    • In the second argument of ‘(<|>)’, namely ‘eof’
      In a stmt of a 'do' block: char '\n' <|> eof
      In the expression:
        do cs <- content `sepby1` comma
           char '\n' <|> eof
           return cs
    |
130 |   char '\n' <|> eof
    |                 ^^^
Failed, no modules loaded.
*Main> parse "a,b,c\n d,e \n a, b" csv
Just ([["a","b","c"],[" d","e "],[" a"," b"]],"")