The title means that there is already a functional pretty printer by Wadler but even though I use OCaml the following code is based on Benjamin Pizza’s Gutenberg library. The paper that shows the imperative version is shown below( Derek C. Oppen, “Pretty Printing” (1979)). But I have not ported the code from the paper.

This is a typical post in this blog in the sense that code is shown first and the narrative is built later if at all. This has its disadvantages as the article is incomplete without the explanation.

Snowflake is a network service for generating unique ID numbers at high scale with some simple guarantees. I am trying to code this in OCaml.

tl;dr

1. The code will be gradually improved and be committed to git finally. The version on this page is compiled but unfinished until I mention it here.
2. Performance considerations are not paramount here. But building lists like this again and again instread of using Array is not at all recommended.

     let n_4keys = List.mapi (fun j el -> if i = j then
                                   List.nth keys (i - 1)
                                  else el) keys in (* TODO Array is mutable and needed here*)
   

1. The algorithm seems complicated and nodes can be added wrongly. But I am trying to test is as thoroughly as possible.
2. My OCaml code is still improving. Loops I code seem to distract from the underlying logic. It should be more functional with proper comments.
3. Almost all unused code is removed so that there are no compiler warnings. There are unused functions though.

This is the second part that shows the OCaml port of F# code that implements a stack-based Virtual Machine. The functors turned out to be very different from the structure of F# code.

Simple Lambda Calculus interpreter

Notwithstanding the loftiness of the title, this is just a tutorial inspired by Implementing a JIT Compiled Language with Haskell and LLVM. I chose OCaml and decided to select my own libraries to accomplish this. So, for example, the parser using Angstrom, which I know nothing about.

An attempt to implement the Raft distributed protocol using OCaml 5 Eio, Effect Handlers, and capnp-rpc-lwt, which is a RPC library based on Eio . Eio allows integration of Lwt framework.

Collaborative editor patterns that I try to code could be of many kinds. There are string manipulation algorithms, CRDTs and even LLM inference. So even though a full-fledged editor is not in scope here, many algorithms like these can be explored and a functional editor can be created.

Storage Engine

I know of a few methods to learn Functional Programming languages. One could read a book or read source code. My attempt involves source code that I port to my favorite language. And I learn two different languages at the same time. The source and the target. It has been very productive for me.

I am reading about Semantics of Programming Languages and here is an attempt to code Racket to parse and interpret toy languages. More details will be added. The code here is not the final version but it compiles. It shows the progress made as I learn the nuances of Racket and types.

Whenever I code Data structures like BTree,LSM etc. in OCaml I read SML,Rust or C++ code. The code I read is in a repo. that implements a caching layer or DBs like https://rethinkdb.com. I don’t find any direct OCaml references. So I ported this Haskell two-three tree by http://matthew.brecknell.net/post/btree-gadt/…. Moreover since I am learning it is hard to identify succinct functional code as some examples seem to be imperative.

tl;dr

1. The code will be gradually improved and be committed to git finally.
2. Performance considerations are not paramount here.
3. The language is OCaml and it is imperative even though I will attempt to use functional Data structures.
4. The repository is this

This is my attempt to code a Ray Tracer in Racket. Details are forthcoming.

I hope to add details as I understand this field better. I may also use multiple languages to code parts of algorithms.

tl;dr

1. The architecture is described in Llama: Open and Efficient Foundation Language Models
2. The code is ported from PyTorch to TensorFlow 2.x using various references. (e.g) https://nn.labml.ai/transformers/rope/index.html TensorFlow is very verbose and sometimes it poses difficulties as every line of PyTorch has to be ported.
3. In very few cases the code can be directly ported with minimal changes. But this situation isn’t common.
4. The math supporting the algorithm is only partially understood. There are several research papers to read.
5. The RoPE embeddings and attention need more insight and explanation.In fact each section will need multiple diagrams and descriptions.

Yet another attempt to closely replicate the popular PyTorch code of https://karpathy.ai/zero-to-hero.html close on the heels of the exploration of basic https://mohanr.github.io/Exploring-Transformer-Architecture/.

I set about learning the Transformer Architecture from first principles. Before long I realized I need to read many Arxiv research papers starting with ‘Attention is All you need’. But there are other older foundational papers dealing with this.

Crafting Interpreters

I started dabbling in Programs and proofs recently by using Spacemacs and its Coq layer. Since I didn’t study this subject before I start by setting up and using the tools.

Spacemacs

As part of my effort to engage with the Open-source community I started answering Stackoverflow questions. I started by asking a few decent questions and then answered some of my own questions and accepted them. Gradually I understood that this community site is not only about answering but also asking good questions that others can answer.

As part of the lecture series this year Yoshua Bengio spoke about Deep Learning research in Chennai. I will add more details gradually as the topics that he covered have to be researched.

Introduction

At this time this article is quite unwieldy and contains hundreds of lines of code without proper explanation. It has to be split up , edited and published as another series. Moreover I learnt more about how to code a functional language by consulting some experts. I will edit it in due course.

In the second part I explain some more language features and code.

Many programming problems lend themselves easily to solutions based on Functional Programming languages. It is not hard to convince ourselves of this after coding a Language like OCaml or Haskell.