#+TITLE: Grasshopper's Monadic Parser
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#+begin_quote
A Parser for Things
is a function from Strings
to Lists of Pairs
of Things and Strings!
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The quote can be found on: [[https://web.archive.org/web/20221206073052/https://www.willamette.edu/~fruehr/haskell/seuss.html][seuss]]! and also you can observe the image
here:

#+CAPTION: Seuss monadic parser post
#+NAME:    Seuss monadic parser post
[[./SeussFinal2.jpeg]]

* Monadic Parsing in Haskell
The majority of tutorials, blog posts, and general information around
the web related to Haskell's Parser Monads always goes back to the
paper: [[https://www.cs.nott.ac.uk/~pszgmh/pearl.pdf][Monadic Parsing in Haskell]] (by Graham Hutton and Erik Meijer).
Like mentioned on the abstract, it's a tutorial on how to define
recursive descent parsers in Haskell, making use of the structuring
capabilities of the language (coff coff Monads). This paper has
literally my age (it was published in 1998), and one could confirm that
it has indeed aged quite gracefully. Although the code associated with
the paper still probably runs with some help, it is a bit outdated in
regards to modern Haskell. If curious about what can be done about this
topic using modern Haskell I can advise on some tutorials:

- [[https://vaibhavsagar.com/blog/2018/02/04/revisiting-monadic-parsing-haskell/][Revisiting 'Monadic Parsing in Haskell']] by [[https://vaibhavsagar.com/][Vaibhav Sagar]]
- [[https://serokell.io/blog/parser-combinators-in-haskell][Parser Combinators in Haskell]] (on [[https://serokell.io/][Serokell]] companie's blog)
- [[https://hasura.io/blog/parser-combinators-walkthrough/][Parser Combinators: a Walkthrough]]
- [[https://cseweb.ucsd.edu/classes/wi13/cse230-a/lectures/lec-parsers.html][CSE230 Wi13 - Monadic Parsing]] (UCSanDiego class on monadic parsing)
- [[https://abhinavsarkar.net/posts/json-parsing-from-scratch-in-haskell/][JSON parsing from scratch in haskell]] by [[https://abhinavsarkar.net/][Abhinav Sarkar]]
* Warning (Warning)
This library is a small project of mine with the intention of learning
and using to implement my interpreters/compilers/etc... It will probably
be always a bit unstable and suffer weird changes. If you want an actual
industry standard parser of this kind you should look for:
[[https://hackage.haskell.org/package/megaparsec][megaparsec]], [[https://hackage.haskell.org/package/parsec][parsec]] or the microscopic version: [[https://hackage.haskell.org/package/yoctoparsec][yoctoparsec]]!