One advantage that is obvious now is that "Char" isn't specified until we define "Buffer", meaning a "Piece" can deal with any datatype, so you can easily get y

One advantage that is obvious now is that "Char" isn't specified until we define "Buffer", meaning a "Piece" can deal with any datatype, so you can easily get your Piece Table to deal with any character format from ASCII, UTF-8, UTF-16, etc. to raw bytes, Hex values, etc. It's even fairly obvious how to merge buffers that use different character formats. The strongest point I see regarding Piece Tables is that Pieces are so discrete. You can define a Piece to be whatever you want it to be, as long as you implement "mappend" for it, or you can put the Piece in a box with other data, and make your buffer a list of boxes, and define "mappend" for the rest of the "box"'s data. Another fairly obvious implementation is an undo/redo tree (like Vim has): Instead of Buffer being a List of Pieces, it can be a Tree of Pieces. The buffer is merged by merging the leftmost leaves of the tree, and "undo" is done by swapping the last left Leaf with an empty Leaf. Redo is done by rotating the last left node's leaves. A final note regarding the above implementation: This simple mappend can only merge Pieces in order. If a Piece tries to edit part of another Piece that doesn't exist (out of bounds), it will be appended, or prepended without any filler, because that is how "splitAt" handles edge cases (rather than being implemented with Maybe). It wouldn't be too difficult to implement "mappend" for these edge cases, but you would need to decide on a filler character like space, or you would have to implement some kind of lazy merge that just keeps the second Piece around until it can be merged.