@counterVariable The grammar is fairly simple, but custom binary operators and precedence can mean there's actually more to keep up with when reading.
As a big fan of Haskell syntax, that is constantly playing around with new languages, are there specific "mistakes" you feel were made, that I might try to avoid in any of my future languages?
No type equalities. For any fixed a, given c :: a -> f a and si :: (forall f r. Functor f => a -> f r -> f (a -> r) provide a runtime value (a Bool) that is True is a is isomorphic to Void and False otherwise.
@BoydStephenSmithJr I thought so too, but then I read your original post again and the hypotheses were stated clearly (well, except for the type mistake 😅 which did probably change quite a lot since it turned a negative a into a positive one)
What would probably have helped me better understand the question is the context, though: how did you encounter that problem?
@glocq I'm off in my own world trying to do some type checking for a dependently-typed core (GRTT) in Haskell but avoiding GADTs (and TypeEquality constraitns) and other GHC-only features.
I'm using bound, so I have a type parameter on terms, contexts, etc. to represent variables, but I'd like to test a context to see if it is empty (as part of checking well-formedness). It's somewhere between checking to see if a bound-style term is closed and seeing if the type parameter to Context is Void.
Anyone in my #haskell (or other, I guess) circles in charge of www.cs.nott.ac.uk ? It was working yesterday, but it keeps timing out (for me) today.
I need to re-read the section of blampied-thesis.pdf on the prefix functor, and especially how it works when the non-uniform type is self-nested in interesting ways.
Trying to do a "project :: t -> f t" and keep getting hung up on the Scope-modified recursions.
Alternatively, is that thesis available elsewhere? I searched, but haven't found.
The term 'telemetry' can raise a lot of concerns, especially within the realm of #OSS. In the latest episode of #TheHaskellInterlude, Joachim Breitner and Andres Löh interview @avi_press, the CEO of @scarf_oss. Learn more about the episode here: https://haskell.foundation/podcast/47/ #Haskell
This is a great blog post on the WellTyped blog on specialization in Haskell! It's a good reminder that I (or someone) should really get around to getting rid of -fexpose-all-unfoldings and -fspecialize-agressively in the Agda codebase.
Helsinki Haskell Users Group's first book club had its conclusion meeting today with Sockets and Pipes coming to its very end. It has been a ride, one with plenty of scheduling difficulties, but I think we only fell like a month and a half from the original planned schedule and actually had a member retention rate of 100% (of members who were there in the beginning, sadly we could not quite make it 133%)!
To talk a bit about the book as a whole, I do feel like I understand Monad Transformers a lot better now though I'll still need to reread the sections introducing them I am sure. ReaderT especially was something I could see was colossally handy, but given it was in the second to last chapter we were already quite deep with trying to understand everything else so the true utility of it remains somewhat hazy despite the quality of the chapter itself which felt higher than those surrounding it. The habit of reading RFCs and attempting to match the spec in the types one writes is also one I should include in my general workflow, though that is probably a no-brainer for most. It just wasn't a thing in my previous work, so bear with me while I call it a novel concept!
I'm still working on my personal project, but getting nix-build working seems difficult. I'll just have to bring it up in the next main group Office Hours meetup I suppose, lest I never get this show on the road!
Only very few breakages from Flora's #Haskell dependencies with GHC 9.10.1-alpha3. We may be able to adopt it as soon as HLS supports it (and a nice dose of "allow-newer" in cabal.project configuration)
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.
New blog post by my colleague Finley on "Choreographing a dance with the GHC specializer (Part 1)". This is in addition to our #Haskell#Unfolder episode on the same topic tomorrow, 2024-04-16, at 1830 UTC on YouTube.
I expect the docker image would contain a GHC that stack would find and use; I am using the matching resolver for the tag (e.g.: 22.17). :blobfoxhappy:
@simonmic Done-ish (mostly linked to my post here)
On a separate note, how portable is my account? I just picked element since it seemed like a zero-install option. If I use matrix more, I might want to switch clients to something that integrates will with KDE.
pseq combinator is used for sequencing; informally, it eval-
uates its first argument to weak-head normal form, and then eval-
uates its second argument, returning the value of its second argu-
ment. Consider this definition of parMap:
parMap f [] = []
parMap f (x:xs) = y ‘par‘ (ys ‘pseq‘ y:ys)
where y = f x
ys = parMap f xs
The intention here is to spark the evaluation of f x, and then
evaluate parMap f xs, before returning the new list y:ys. The
programmer is hoping to express an ordering of the evaluation: first
spark y, then evaluate ys.
The obvious question is this: why not use #Haskell’s built-in seq
operator instead of pseq? The only guarantee made by seq is that
it is strict in both arguments; that is, seq a ⊥ = ⊥ and seq ⊥
a = ⊥. But this semantic property makes no operational guaran-
tee about order of evaluation. An implementation could impose this
operational guarantee on seq, but that turns out to limit the optimi-
sations that can be applied when the programmer only cares about
the semantic behaviour. Instead, we provide both pseq and seq
(with and without an order-of-evaluation guarantee), to allow the
programmer to say what she wants while leaving the compiler with
as much scope for optimisation as possible. https://simonmar.github.io/bib/papers/multicore-ghc.pdf
After extensively using the #lens#Haskell library for half a year at work I have now played around with the #optics library again. I am amazed by how much more helpful error messages are with #optics. It’s an amazing library and I would recommend it over #lens whenever you have the choice.
@mangoiv Hasn’t been my impression with #optics yet. To me it feels like the type level stuff is "finished". As long as you only define and use existing types of optics you don’t need to worry about it.
