First, the boring, not over-the-top version: the Stack team is starting a new initiative, the Stack Issue Triagers. We’re asking for volunteers to go through the Stack issue tracker on Github and help users with support questions get moving more quickly, and alert the development team of bugs that require their attention. A more advanced […]
Let’s say we’re going to be writing some code that needs to know the current time. It would be inefficient to have to recalculate the current time whenever it’s demanded, assuming we demand it more than once per second. Instead, it would be more efficient to have a variable that gets updated once per second. […]
I’d really intended to write a blog post on a different topic this week. But given that I did some significant refactoring in the Stack codebase related to a number of recent posts, let’s just knock this one out and get to other topics another time. I’ve played with the idea of a RIO (Reader […]
For the past few years, Francesco Mazzoli and I have discussed issues around monad transformers—and the need to run their actions in IO—on a fairly regular basis. I wrote the monad-unlift library a while ago to try and address these concerns. But recent work I did in Stack on the extensible snapshots branch demonstrated some […]
NOTE This blog post made the rounds last week before the branch was actually merged and the post was still on a review server. I’m officially publishing it as the pull request is now merged. There is a collection of features in Stack that have been added in bit by bit, as opposed to being […]
Streaming data is a problem domain I’ve played with a lot in Haskell. In Haskell, the closest we come to built-in streaming data support is laziness-by-default, which doesn’t fully capture streaming data. (I’m not going into those details today, but if you want to understand this better, there’s plenty of information in the conduit tutorial.) […]
This is a debugging story told completely out of order. In order to understand the ultimate bug, why it seemed to occur arbitrarily, and the ultimate resolution, there’s lots of backstory to cover. If you’re already deeply familiar with the inner workings of the monad-control package, you can probably look at a demonstration of the […]
This blog post came out of two unrelated sets of questions I received last week about usage of the resourcet library. For those unfamiliar with it, the library is often used in combination with the Conduit streaming data library; basically every conduit tutorial will quickly jump into usage of the resourcet library. Instead of just […]
Often times I’ll receive or read questions online about “design patterns” in Haskell. A common response is that Haskell doesn’t have them. What many languages address via patterns, in Haskell we address via language features (like built-in immutability, lambdas, laziness, etc). However, I believe there is still room for some high-level guidance on structuring programs, […]
In the last post, we covered the following: What purity is and what it isn’t. We looked at functions and function composition. We’ve looked at how reasoning is easier if you only have functions. In this post, we’ll explore: SQL as a pure language, which is a familiar language to almost everybody. How pure languages […]