Posts by Rudi Grinberg

Deriving Slowly

There’s been some recent grumbling about the usability of ppx in OCaml, and instead of just letting it slide again, I’ve decided to do something constructive about this and write a little tutorial on how to write a deriving plugin.

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Creating Static Linux Binaries in OCaml

Creating truly static binaries for Linux like golang is a capability that is occasionally useful. I’ve seen questions about it on IRC a few times, and I’ve personally found this approach is particularly useful when deploying to environments where installing libraries isn’t easy, such as AWS Lambda. Unfortunately for me, the approach that I will explain in this article wasn’t as approachable. So I’ve prepared a quick tutorial on how to easily create a static binary in OCaml and test it.

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Cohttp Packaging Breakage Ahead

As a follow up to my previous post regarding optional dependencies, I’d like to expand on how my advice will be followed in practice in the context of the cohttp library.

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Optional Dependencies Considered Harmful

This will be a short PSA to opam package maintainers to avoid spurious optional dependencies. At this point, I think this is all relatively common knowledge. But open source maintainers are as a rule busy people, and without much encouragement, they end up dragging their feet. Therefore I hope this post can be a useful reminder of the negative effects of optional dependencies and what can be done to avoid them.

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Searching the load-path

Here’s another tip for taming your Emacs config. In particular, how to search the huge body of elisp that is present with most Emacs installs - the load-path. While the load-path is a very important collection of directories, searching it isn’t as easy and accessible as it should be. As usual, Emacs compensates with plugins:

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Spacemacs Useful Buffers Gotcha

I’ve ran into a little spacemacs annoyance that took me a while to resolve, and it seems like it could pop up under a variety of different contexts. I figured that a few words about it here might save others some time.

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Pretty Printing a Table in Emacs

Recently, I needed to output some relatively small tabular data in Emacs and message was starting to be a bit long in the tooth. Finally, I’ve decided to try my hand at upgrading the visuals for myself. I realize that there’s probably dozens of different ways of pretty-printing tables in Emacs, but I was already partial to the tabular output used by functions such as list-processes and plugins such as prodigy (Using org mode’s tables also comes to mind for example). So I’ve decided to recreate this experience for my own tables. The result has been convenient and aesthetically pleasing enough to share.

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Free Monads in the Wild - OCaml Edition

OCaml programmers don’t seem to resort to free monads much. I like to imagine that this is the case because we’re a practical bunch. But it could simply be that this technique like other monads is a bit heavyweight syntactically, let alone the performance implications it might have.

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Publishing an OPAM Package - a Checklist

The process of publishing an opam package has come a long way from its modest beginnings. Nevertheless the opam team deserves praise for choosing an extremely simple and flexible model for contribution - the git commit. To me that explains how it aged gracefully with improvements such as:

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Scrap your Camlp4

ppx has been out for a while but it seems like the community has been taking its time transitioning away from camlp4. There’s probably a couple of reasons for that:

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Omegle in N2O

Recently I’ve been messing around with a new and exciting web framework in erlang called N2O. This framework appeals to me for a few reasons. These include:

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Type Safe Routing - Baby Steps

Type safe routing means different things to different people. So let’s start by clarifying the intended meaning in this post. There are 2 widely used definitions:

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Abandoning Async

There is an old and great schism in the OCaml community. The schism is between two concurrency libraries - Async and Lwt. As usual for these things, the two are very similar, and outsiders would wonder what the big deal is about. The fundamental problem of course is that they’re mutually incompatible. The result of this is a split OCaml world with almost no interoperability, and duplication of efforts.

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Introducing Humane-re

OCaml is my favorite language, but one area where it (its tools rather) often falls short in practice is common string handling tasks where regular expressions are often involved. The kind of stuff that Awk and and scripting languages often get praised for. In other words, not getting in the way and allowing to get the job done with minimal boilerplate.

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Middleware in Opium

In my previous post I’ve introduced opium in a beginner friendly way, while in this post I’ll try to show something that’s a little more interesting to experienced OCaml programmers or those are well versed with protocols such as Rack, WSGI, Ring, from Ruby, Python, Clojure respectively.

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Introducing Opium

One itch that I usually need to scratch is setting up quick and dirty REST API’s - preferably in OCaml. OCaml does have a few options for web development but I found them to be not so great fits for my needs. To summarize:

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Omegle clone in Flask + Gevent + WebSockets

Python ranks fairly high when it comes getting things done without too much ceremony in the programming community. I briefly had some doubts of this assertion of until I finally found Flask-Sockets. This small library makes it very natural to serve WebSockets in Flask/gevent. You can consider this blog post as an advertisement for this small but extremely useful library.

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Benchmarking OCaml Json Libraries

According to opam OCaml has 2 popular libraries for parsing json:

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Document Search Using Cosine Similarity In Haskell Using Linear

Reading OCharles’ excellent series about 24 days of hackage, in particular the post about Linear, I’ve been inspired to revisit some old code I wrote. The code is a document search engine that uses cosine similarity to rank matches. I like the following two articles if you’re not familiar with this technique:

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Lru Cache With a Memcache-Like Interface

Lately, I’ve been messing around with Janestreet’s core and async libraries by reimplementing an old interview question that has been posed to me before. The problem statement itself is from my memory alone so this isn’t 100% what I’ve been asked but it should be extremely close.

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