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module Buffer where
-- Type class for data structures that can represent the text buffer
-- of an editor.
class Buffer b where
-- | Convert a buffer to a String.
toString :: b -> String
-- | Create a buffer from a String.
fromString :: String -> b
-- | Extract the nth line (0-indexed) from a buffer. Return Nothing
-- for out-of-bounds indices.
line :: Int -> b -> Maybe String
-- | @replaceLine n ln buf@ returns a modified version of @buf@,
-- with the @n@th line replaced by @ln@. If the index is
-- out-of-bounds, the buffer should be returned unmodified.
replaceLine :: Int -> String -> b -> b
-- | Compute the number of lines in the buffer.
numLines :: b -> Int
-- | Compute the value of the buffer, i.e. the amount someone would
-- be paid for publishing the contents of the buffer.
value :: b -> Int
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