I built a compiler and interpreter for a statically typed but fully inferred functional programming language in OCaml a while ago: https://github.com/coetaur0/nox The project is fairly simple, but there are non-trivial parts such as the type-system's implementation that might be worth looking at.

I'm sure a lot of people here have much better examples, but I wrote some basic regular expression and finite automata algorithms in Haskell a long time ago:

https://github.com/jl2/Compiler-Algorithm-Code/tree/master/h...

I tried it out and after renaming fold -> foldr, it still builds and seems to work. The main function takes a regex as a command line argument and creates a finite automata graph using GraphViz's dot.

In the Compiler-Algorithm-Code/haskell directory:

    make
    ./test "(foo)+(bar)*(foo+)" | dot -Tpdf -ofoobarfoo.pdf && xdg-open foobarfoo.pdf

The are LLVM Caleidoscope (toy compiler) in both Haskell and OCaml

https://github.com/sdiehl/kaleidoscope https://github.com/arbipher/llvm-ocaml-tutorial

The Haskell one is a nice one. Can say nothing about the OCaml one since I found it using a google search.

I've had a try at implementing an Caleidoscope compiler in OCaml but did not finish it. But it was fun to write.

I wrote this like ~10 years ago as a "Hello World++" type demo (basic key/value server) in Haskell. It's about 200 LoC, with a Haskell and Python client. http://github.com/wyager/neks

Some time ago I made a chip-8 emulator with haskell https://github.com/EzequielRamis/chisito. I suppose it may be easier the state management in ocaml.

I released a game using OCaml bindings to the Raylib library. I had never written OCaml before and I didn't spend very much time refactoring, so the code is pretty messy and maybe isn't the best example of the language. But some of it turned out pretty nice - the first ~90 lines of this file detect collisions between two shapes using the Separating Axis theorem: https://github.com/mega-dean/hallowdale/blob/main/src/collis...

This should be short enough to read: https://github.com/Artamus/git-split/

https://github.com/matthiasgoergens/Div7 is a simple one that you might like.

I wrote a Lox compiler and interpreter in OCaml a few years ago: https://github.com/gaultier/lox-ocaml

No idea how it holds up, it was my first try at a compiler, but it’s quite small. I was following the Crafting Interpreters book.

You can check my (not finished) example of GitHub TUI built in OCaml:

https://github.com/chshersh/github-tui

An unfinished command-line client for Hacker News:

https://github.com/LucianU/hn-reader