chapter 6.8 in version 12.0

[elephanter]

instance streamString :: Stream String Char where
  uncons = String.uncons

Failed to compile with error "Could not match type CodePoint with type Char" I have to replace that code into

instance streamString :: Stream String Char where
    uncons "" =  Nothing
    uncons s = Just {head: charAt 0 s, tail: String.drop 1 s}

to make it work