Ropes ("heavyweight strings") for OCamlhttps://github.com/Chris00/ocaml-rope
Ropes ("heavyweight strings") are a scalable string implementation:
they are designed for efficient operation that involve the string as
a whole. Operations such as concatenation, and substring take time
that is nearly independent of the length of the string. Unlike
strings, ropes are a reasonable representation for very long strings
such as edit buffers or mail messages.