This blog post was entirely inspired by reading the GATs on Nightly! Reddit post by /u/C5H5N5O. I just decided to take things a little bit too far, and thought a blog post on it would be fun. I want to be clear from the start: I'm introducing some advanced concepts in this post that rely on unstable features in Rust. I'm not advocating their usage at all. I'm just exploring what may and may not be

This blog post is a direct follow up on my previous blog post on different levels of async in Rust. You may want to check that one out before diving in here. Alright, so now we know that we can make our programs asynchronous by using non-blocking I/O calls. But last time we only saw examples that remained completely sequential, defeating the whole purpose of async. Let's change that with something

First there was cooperative multiprocessing. Then there were processes. An operating system could run multiple processes, each performing a series of sequential, blocking actions. Then came threads. A single processes could spawn off multiple threads, each performing its own series of sequential, blocking actions. (And really, the story starts earlier, with hardware interrupts and the like, but ho

This is a story about how some bad API design on my part caused some ugly race conditions that were very tricky to break down. I’m writing this story as a word of warning to others! The code itself was written in Haskell, but the lessons apply to anyone working with Unix-style processes. Introducing typed-process I maintain both the process library in Haskell, which is the standard way of launchin

We’re big fans of safety-focused languages at FP Complete. As our previous blog post comparing Rust and Haskell made clear, we think both of these are great languages. A recurring theme we have for both internal and client projects is: which language should we use? The general guidelines in that blog post apply: If there’s a specific requirement (e.g., hard realtime) that prefers avoiding garbage

FP Complete is known for our best-in-class DevOps automation tooling in addition to Haskell. We use industry standards like Kubernetes and Docker. We’re always looking for new developments in software that help us empower our clients. Rust is an up-and-coming programming language whose history starts in 2010. Rust has much overlap in its strengths with Haskell. We are impressed with Rust’s tooling

In the past few months, and in particular in the past two weeks, I’ve gotten a number of people asking me the question: Is Rust a functional programming language? This makes sense: I’m a big advocate of functional programming, I work at a company with FP in its name, my primary programming language is Haskell, and yet I use and enjoy Rust. So is Rust consistent with everything else in my FP-centri

Concurrent programming is hard! I still remember the moment of my introduction to multi-threaded programming at the University of New Mexico, our professor grabbed his head and said: “Here be demons!”. There are all sorts of issues that arise in a concurrent setup, such as race conditions, starvation, deadlocks, data corruption, you name it. All of these are also applicable to Haskell, and in this

This is a short and non-technical blog post demonstrating why the Haskell programming language is a good choice for building cryptocurrencies. Cryptocurrencies are not your average software Cryptocurrencies are different from other programs in one key way: One mistake in the code can result in the instantaneous loss of all value of all users. This is not often the case with other software. In conv

We launched our monthly webinar series on Wednesday, April 11th with our first webinar on How to Handle Asynchronous exceptions in Haskell. This webinar was the first in what will be a monthly series covering topics in Haskell Programming, DevOps, Cloud Computing, Cryptocurrencies, FinTech, Medical Device Software, DataOps, and all the other great things we do. Webinar series launch is a huge succ

I’m pleased to announce the release of a Haskell library for connecting to SQL Server databases via ODBC. Features The library is very simple, but what it does support should be high quality: Correct Unicode handling. All text is handled through the Text type. The test suite randomly generates Unicode to send to the server and query back in a roundtrip. A very simple API: simply connect, execute o

One aspect of Haskell that many new users find difficult to get a handle on is operators. Unlike many other languages, Haskell gives a lot of flexibility to developers to define custom operators. This can lead to shorter, more elegant code in many cases. For example, compare these three equivalent pieces of code: v1 = mappend (mappend "hello " "there ") "world" v2 = "hello " `mappend` "there " `ma

Cardano enlists FP Complete for independent 3rd Party Audit of Cardano Blockchain FP Complete Development specialists will provide comprehensive review of Cardano’s code and technical documentation Zug, Switzerland,24 January 2018—Cardano Foundation, the objective organisation supporting leading blockchain Cardano, has appointed FP Complete, an IT engineering specialist, to provide an independent

In this blog post we will show an example of how we can use Docker to build Haskell applications which we then ship inside Docker images. We will observe two cases. First, we will explore the case of developing on the same Linux distro that we are using for deployment (eg. FROM ubuntu:16.04), and then we will observe the case where we are not developing on a Linux distro but are still targeting Li

I was recently doing a minor cleanup of a Haskell codebase. I started off with some code that looked like this: runConduitRes $ sourceFile fp .| someConsumer This code uses Conduit to stream the contents of a file into a consumer function, and ResourceT to ensure that the code is exception safe (the file is closed regardless of exceptions). For various reasons (not relevant to our discussion now),

Haskell is—perhaps infamously—a lazy language. The basic idea of laziness is pretty easy to sum up in one sentence: values are only computed when they’re needed. But the implications of this are more subtle. In particular, it’s important to understand some crucial topics if you want to write memory- and time-efficient code: Weak head normal form (WHNF) versus normal form (NF) How to use the seq an

The exceptions package provides three typeclasses for generalizing exception handling to monads beyond IO: MonadThrow is for monads which allow reporting an exception MonadCatch is for monads which also allow catching a throw exception MonadMask is for monads which also allow safely acquiring resources in the presence of asynchronous exceptions For reference, these are defined as: class Monad m =>

The other day I threw together a quick program to solve an annoyance some people on our team were expressing. We sometimes do our development on remote machines, but would still like to use local file editors. There are plenty of solutions for this (SSHFS, inotify+rsync), but none of us ever found a prebaked solution that was low-latency and robust enough to use regularly. The program I put togeth

Haskell is an amazing language. With its extremely powerful type system and a pure functional paradigm it prevents programmers from introducing many kinds of bugs, that are notorious in other languages. Despite those powers, code is still written by humans, and bugs are inevitable, so writing quality test suites is just as important as writing an application itself. Over the course of history bugg

Applied Haskell is a commercial training program focusing on teaching intermediate Haskell. The goal is to help someone move from knowing Haskell basics to being able to write commercial software, with enough knowledge to pick up any new skills needed on demand. If you’re new to Haskell, please check out our learning page for introductory material. The content below is freely available. If you’re