Convert OPML to TEXT HADDOCK

OPML, or Outline Processor Markup Language, is a file format utilized primarily for outlining data structures. Initially developed in 2000 by UserLand Software, OPML was designed to facilitate the exchange of outline-based information between different software applications. Its uses have expanded over time, notably in organizing RSS feed lists and managing hierarchical data. The OPML file extension denotes XML-based documents that offer simplicity and interoperability in transferring structured information across diverse platforms. In essence, OPML serves as a versatile tool in the realm of data organization and syndication.

The TEXT file extension, associated with Haddock Markup Language, is used for documentation in Haskell programming. Haddock is a tool for generating documentation from annotated Haskell source code. It uses a lightweight markup language, similar to LaTeX, to format the documentation. The history of Haddock dates back to its creation by Simon Marlow and others as part of the GHC (Glasgow Haskell Compiler) project. It has since become a standard tool in the Haskell community for creating comprehensive and readable documentation.