News about the Haskell programming language from 2024-05-30.

In this episode we talk with David Christiansen, he wrote the books Functional Programming in Lean and the Little Typer.

He has also worked as the Executive Director of the Haskell Foundation, at Galois and did his PhD developing a bunch of cool stuff for Idris.

David is a super upbeat person and I feel that we could spend hundreds of hours talking about Functional Programming Writing and Dependent Types, and we still wouldn’t run out of topics!

News about the Haskell programming language from 2024-05-16.

Wouter and Joachim interview Arseny Seroka, CEO of Serokell. Arseny got into Haskell because of a bet over Pizza, fell for it because it means fewer steps between his soul and his work, and founded Serokell because he could not get a Haskell job. He speaks about the business side of a Haskell company, about the need for more sales and marketing for Haskell itself, and about the Haskell Developer Certification.

h/t @bgamari@mastodon.social

News about the Haskell programming language from 2024-05-02.

ghc-debug is a debugging tool for performing precise heap analysis of Haskell programs (check out our previous post introducing it). While working on Eras Profiling, we took the opportunity to make some much needed improvements and quality of life fixes to both the ghc-debug library and the https://hackage.haskell.org/package/ghc-debug-brick
terminal user interface.

To summarise,

• ghc-debug now works seamlessly with profiled executables.
• The ghc-debug-brick UI has been redesigned around a composable, filter based workflow.
• Cost centers and other profiling metadata can now be inspected using both the library interface and the TUI.
• More analysis modes have been integrated into the terminal interface such as the 2-level profile.

This post explores the changes and the new possibilities for inspecting the heap of Haskell processes that they enable. These changes are available by using the 0.6.0.0 version of
https://hackage.haskell.org/package/ghc-debug-stub and https://hackage.haskell.org/package/ghc-debug-brick-0.6.0.0.

I've mentioned my new effect system, Bluefin, a few times on this forum. It's now ready for me to announce it more formally.

Bluefin's API is differs from all prior effect systems in that it implements a "well typed Handle/Services pattern". That is, all effects are accessed through value-level handles, which makes it trivial to mix a wide variety of effects, including:

• Bluefin.EarlyReturn, for early return
• Bluefin.Exception, for exceptions
• Bluefin.IO, for I/O
• Bluefin.State, for mutable state
• Bluefin.Stream, for streams

If you're interested then read the Introduction to Bluefin. I'd love to know what you all think.

News about the Haskell programming language from 2024-04-18.

This is the first of a two-part series of blog posts on GHC specialization, an optimization technique used by GHC to eliminate the performance overhead of ad-hoc polymorphism and enable other powerful optimizations. There will also be a Haskell Unfolder episode about this topic.

This fuses:

[(x, y) | x <- [0 .. 10], y <- [0 .. 10]]

But this does not:

liftA2 (,) [0 .. 10] [0 .. 10]

Because the latter inlines to:

let xs = [0..10]; ys = [0..10] in xs >>= \x -> ys >>= \y -> (x, y)

And GHC is afraid to push the ys binding into the \x -> ... lambda because that might duplicate the work of evaluating [0..10]. Even though in the end fusing everything would be beneficial.

See: https://gitlab.haskell.org/ghc/ghc/-/issues/24663

Declarative vs imperative:

let v = sum [ ((x ! i) - m) ^ 2 | i <- [0 .. cc - 1] ] / fromIntegral cc

float v = 0.0f;
for (int i = 0; i < C; i++) {
    float xshift = x[i] - m;
    v += xshift * xshift;
}
v = v/C;

#haskell

News about the Haskell programming language from 2024-04-11.

News about the Haskell programming language from 2024-04-04.

Roman, known better online as effectfully, is interviewed by Wouter and Joachim. On his path to becoming a Plutus language developer at IOG, he learned English to read Software Foundations, has encountered many spaceleaks, and used Haskell to prevent robots from killing people.

News about the Haskell programming language from 2024-03-28.

Logs are a critical thing in production systems and I would like to start a discussion about bringing low-level support for efficient logging into GHC

News about the Haskell programming language from 2024-03-21.

When composing several list-processing functions, GHC employs an optimisation called foldr-build fusion. Fusion combines functions in such a way that any intermediate lists can often be eliminated completely. In this episode, we will look at how this optimisation works, and at how it is implemented in GHC: not as built-in compiler magic, but rather via user-definable rewrite rules.