Applications that need to communicate with the outside world inadvertently end up accumulating a range of dependencies – things like database connection-strings, logging facilities, or configuration options.

At work, we are heavy users of the OCaml Lwt library for promised based concurrent programming. Lwt is popular, actively developed, has exceptional performance, and can run on different platforms!

Parser combinators are sets of functions for building parsers in a composable fashion. Haskell’s Parsec library and OCaml’s Angstrom are two examples. Both of these libraries expose monadic interfaces for describing context-sensitive grammars. This post looks at implementing a more restricted parsing library, structured around applicative functors rather than monads.

The next major release of the OCaml compiler, version 4.08, will be equipped with a new syntax extension for monadic and applicative composition. Practically it means that it will be a bit more convenient to work with APIs structured around these patterns. The design draws inspiration from ppx_let but offers lighter syntax, and removes the need of running the code through a ppx preprocessor.

Memoization is a strategy for preventing values to be computed multiple times. The sledgehammer approach in OCaml is a function with the signature:

Following is a continuation of the topic of modular implicits , introduced in the previous post on implicit functors. This time we’ll look at how the extension can help simplifying lenses. I covered lenses in OCaml lenses via modules, where a rather verbose definition of a (van Laarhoven) lens was given in the form of a module signature LENS:

Modular implicits is an experimental feature of OCaml that has yet to land on the master branch. In this and upcomings posts I’m going to give a few examples of what it brings to the table. For an introduction to the topic it’s best to read the original paper.

Lenses, often described as first class getters and setters, can help simplify code for manipulating nested data structures. In this post I’m going to look at how to map the most popular Haskell representation, van Laarhoven lenses, to OCaml.

A few weeks ago I came across a logic puzzle handed out as a holiday challenge. I didn’t solve it by hand but instead turned to Haskell for some help. As it proved to be a fun exercise I decided to pass it on and invited some friends to contribute with solutions in a language of their choice. I here present the given puzzle along with the set of submissions received.

The following is a write-up on an implementation of the Knuth-Morris-Pratt (or KMP) text search algorithm in OCaml. The algorithm itself is rather straight forward but implementing it in a functional style serves as a good example of how lazy data structures may be used as an optimization technique.