Today, 2025-07-23, at 1830 UTC (11:30 am PDT, 2:30 pm EDT, 7:30 pm GMT, 20:30 CET, …) we are streaming the 47th episode of the Haskell Unfolder live on YouTube.
Pure parallelism (Haskell Unfolder #47)
“Pure parallelism” refers to the execution of pure Haskell functions on multiple CPU cores, (hopefully) speeding up the computation. Since we are still dealing with pure functions, however, we get none of the problems normally associated with concurrent execution: no non-determinism, no need for locks, etc. In this episode we will develop a pure but parallel implementation of linear regression. We will briefly recap how linear regression works, before discussing the two primitive functions that Haskell offers for pure parallelism:
parandpseq.
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.