The Haskell Unfolder Episode 30: runST

Today, 2024-07-31, at 1830 UTC (11:30 am PDT, 2:30 pm EDT, 7:30 pm BST, 20:30 CEST, …) we are streaming the 30th episode of the Haskell Unfolder live on YouTube.

The Haskell Unfolder Episode 30: runST

In Haskell, the ST type offers a restricted subset of the IO functionality: it provides mutable variables, but nothing else. The advantage is that we can use mutable storage locally, because unlike IO, ST allows us to escape from its realm via the function runST. However, runST has a so-called rank-2 type. In this episode, we will discuss why this seemingly complicated type is necessary to preserve the safety of the operation.

About the Haskell Unfolder

The Haskell Unfolder is a YouTube series about all things Haskell hosted by Edsko de Vries and Andres Löh, with episodes appearing approximately every two weeks. All episodes are live-streamed, and we try to respond to audience questions. All episodes are also available as recordings afterwards.

We have a GitHub repository with code samples from the episodes.

And we have a public Google calendar (also available as ICal) listing the planned schedule.

There’s now also a web shop where you can buy t-shirts and mugs (and potentially in the future other items) with the Haskell Unfolder logo.