On Wednesday, 2024-05-15, at 1830 UTC, we'll stream the 25th episode of the #Haskell#Unfolder. This episode should be interesting for Haskellers and non-Haskellers alike. Edsko and I will translate a #gRPC server from #Java to Haskell, contrasting the programming paradigms.
Note to self: type variables in #purescript and #haskell cannot be bound to partially applied type synonyms.
If you try to do so, in a sufficiently polymorphic way, you'll get very confusing type errors as the checker attempts to solve things with the variable bound to the "head" of the (parametrically expanded) type alias.
Last night it was (forall r. (forall f. Foldable1 f => f a -> r) -> r) and tonight it was (a -> Term a). Introducing a newtype can help, but beware impredicativity.
Last week I prototyped a git remote helper in a shell script, and now I'm rewriting that in #haskell as part of #gitAnnex.
I don't do this often and I wonder if it was a mistake, probably I should have written the prototype in haskell and then integrated it into git-annex. It's kind of amazing how a lot of complexity is melting away and also how I'm adding So Many Types and also throwing in a lot of robustness improvements.
;; Getting rid of explicit indexing was just step one.
-- After a few days/months/years, I now realize that it is more important and less buggy if I think only of the function to call (and whether I want to end up with a new (maybe pruned) collection, a single thing, or "both" (that's how I think of scans))
@aksharvarma Loop bodies are F-algebras and the "collection" over which you loop is a fixpoint of F. The #haskell recursion-schemes library handles that when F is an endofunctor on the term/expression category in your language.
You can still apply algebra semantics for "higher" functors F (when F is "really"/also a [type-indexed] functor family) with the appropriate Kan extensions.
I do know that maps/folds/etc. can be generalized to anything belonging to the functor class in #haskell; so things like trees and other "container" type things beyond just lists. However, I didn't want to introduce special terminology in what was otherwise free of such jargon.
As for the rest of what you said, I don't know enough category theory to understand what you meant, although I can recognize them as being category theory terms.
Thanks for pointing out the connections. Hopefully, one day I'll get to a level of understanding where I can grok what you said.
The #Haskell#Unfolder is now 1 year old! In the anniversary episode, Edsko and I will return to the very first topic and consider (un)folds, but now in a more generic setting. Live on YouTube 2024-05-01 at 1830 UTC.
Brisbane Functional Programming Group #BFPG May meetup, Tue 14th: #Gleam v1 (Rob Ellen) + Do your taxes with #Haskell (Fraser Tweedale). All curious minds are welcome!
I wanted to declare something of type Code m a -> m Exp so I can pass the type variable of the typed code to a function used within the untyped code (which I have to do because TTH will not allow me a polymorphic function where I don’t name all type variables in the AST within the Code) but of course this doesn’t work because „untyped code cannot appear in type splice“ ARGH #haskell
#Haskell, #Jones, #Texas National Weather Service: #TORNADO WARNING in this area until 11:15 PM CDT. Take shelter now in a basement or an interior room on the lowest floor of a sturdy building. If you are outdoors, in a mobile home, or in a vehicle, move to the closest substantial shelter and protect yourself from flying debris. Check media. Source: NWS San Angelo TX