- Haskell-Cafe - Haskell.org

Re: [Haskell-cafe] Should GHC 9.4.7 be native on MacBook Air M2?
by David Banas 28 Oct '23

28 Oct '23

Ah, I needed this line in my stack.yaml file: arch: aarch64 Why is that? Shouldn’t it use the native architecture if it can support it? -db

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Should GHC 9.4.7 be native on MacBook Air M2?
by David Banas 28 Oct '23

28 Oct '23

I’m working on a new MacBook Air M2. I just bumped my current Haskell project to stack LTS-21.17, after catching up on the GHC porting effort news. I did a stack clean / stack build and saw GHC 9.4.7 being installed, as expected, but still to the x86_64-osx directory: % l ~/.stack/programs x86_64-osx % l ~/.stack/programs/x86_64-osx ghc-8.10.3 ghc-8.10.4.tar.bz2 ghc-8.6.3.installed ghc-9.0.2 ghc-9.2.2.tar.bz2 ghc-9.2.7.installed ghc-8.10.3.installed ghc-8.4.3 ghc-8.6.3.tar.bz2 ghc-9.0.2.installed ghc-9.2.5 ghc-9.2.7.tar.bz2 ghc-8.10.3.tar.bz2 ghc-8.4.3.installed ghc-8.6.5 ghc-9.0.2.tar.bz2 ghc-9.2.5.installed ghc-9.4.7 ghc-8.10.4 ghc-8.4.3.tar.bz2 ghc-8.6.5.installed ghc-9.2.2 ghc-9.2.5.tar.bz2 ghc-9.4.7.installed ghc-8.10.4.installed ghc-8.6.3 ghc-8.6.5.tar.bz2 ghc-9.2.2.installed ghc-9.2.7 ghc-9.4.7.tar.bz2 I was expecting a native version; do I misunderstand something?

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Simplest way to move a ... `using` ... line into the IO monad?
by David Banas 27 Oct '23

27 Oct '23

Hi all, What is the simplest way to translate a non-monadic line of Haskell code, such as: res = map foo xs `using` parList rseq For use in the IO monad? This doesn’t work: res <- mapM fooM xs `using` parTraversable rseq complaining: No Traversable instance for IO. Thanks, -db

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Re: [Haskell-cafe] when does ghc(i) expand type synonyms?
by Olaf Klinke 26 Oct '23

26 Oct '23

> ghci> :set +t > > ghci> "foo" > "foo" > it :: String > > ghci> reverse "foo" > "oof" > it :: [Char] I'm not a GHC expert, but my guess is: It must have something to do with unifying the argument types with the type signature of the function. In (<>), the two argument and the result types are identical. Hence it can be safely said that x <> whatever as long as this expression is valid, has the same type as x. In contrast, the result type of (++) is always of the shape [a]. Hence String gets unified with [a] which forces expansion of the type synonym. Consider: class Foo a where {rev :: a -> a; conc :: a -> a -> a} instance Foo [a] where {rev = reverse; conc = (++)} revconc :: Foo a => a -> a; revconc a = conc a (rev a) :t revconc ("foo" :: String) revconc ("foo" :: String) :: String So as long has you hide (++) in a type signature that proves input and output are the same, synonyms don't get expanded. Olaf

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when does ghc(i) expand type synonyms?
by Johannes Waldmann 25 Oct '23

25 Oct '23

Dear cafe, my students were asking: why are types printed differently here? ghci> :set +t ghci> "foo" "foo" it :: String ghci> reverse "foo" "oof" it :: [Char] ... and I add ghci> fst ("foo", 42) "foo" it :: String compiler docs do not really explain the difference https://downloads.haskell.org/ghc/latest/docs/users_guide/ghci.html#ghci-cm… (it says "display the type of .." while technically it is "display some representation of the type of ..."?) I found this explanation of a somewhat related issue https://gitlab.haskell.org/ghc/ghc/-/issues/9183#note_83743 While playing around with this, I noticed: ghci> let x = "foo" in (x <> reverse x) "foooof" it :: String ghci> let x = "foo" in (x ++ reverse x) "foooof" it :: [Char] Well, it's just optics: when I extract the type programmatically, the synonym necessarily does get expanded ghci> import Data.Data ghci> typeOf (let x = "foo" in (x <> reverse x)) [Char] it :: TypeRep - Johannes

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Hackage not building package
by Ivan Perez 23 Oct '23

23 Oct '23

Hi, I recently uploaded a package ( https://hackage.haskell.org/package/dunai-0.12.0) and hackage is not building it. I don't see info anywhere and I cannot re-trigger a build: attempting to do so shows the message "Report not found -Build report does not exist" Is everything ok with hackage? Thanks Ivan

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Where did pem-0.2.4 come from? a.k.a. is anyone compelled to take-over this project?
by Noon van der Silk 19 Oct '23

19 Oct '23

Glancing at hackage, I happened to noticed that pem is at 0.2.4 - https://hackage.haskell.org/package/pem-0.2.4 Glancing at the repo, I notice that pem is at 0.2.3 - https://github.com/vincenthz/hs-pem It seems there _is_ a tag for 0.2.4, but `master` has not been updated <https://github.com/vincenthz/hs-pem/compare/master..pem-v0.2.4>. Is there anyone out there that feels compelled or excited to fix this? And perhaps relatedly, given vincent has archived all these repos; perhaps there could be a kind of "global takeover" by the HF cryptography working group of these projects? -- Noon van der Silk, ن http://silky.github.io/ "My programming language is kindness."

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Request for take over: graphviz
by Daniel Casanueva 18 Oct '23

18 Oct '23

Hello, graphviz [1] maintenance has been inactive for a long time now. Revisions have been published, but the maintainer seems unresponsive. Last year, Bodigrim suggested the package needs a new maintainer in a GitHub thread [2] that one month ago I found while looking if someone had already done the fix I needed. I'm happy to help keeping the package alive so, about a month ago, I emailed Ivan (graphviz's author) to the e-mail address from his GitHub profile, offering my assistance with graphviz. I haven't gotten any answer yet, so I thought I should be making my offer public, as indicated by the "Taking over a package" wikipage [3]. I don't have big change plans for graphviz. Most likely I will just be patching it to keep it working with future GHC releases and reviewing/accepting PRs. Thank you, Daniel [1] https://hackage.haskell.org/package/graphviz [2] https://github.com/ivan-m/graphviz/pull/53#issuecomment-1261496914 [3] https://wiki.haskell.org/Taking_over_a_package

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Assistant Prof at Barnard College, Columbia U
by Mark Santolucito 17 Oct '23

17 Oct '23

Hi all, Barnard College, Columbia University has an opening for an Assistant Professor: https://cs.barnard.edu/assistant-professor-computer-science-2024 The deadline is Oct 27 for full consideration. Barnard is the women's college of Columbia and has a 2-2 teaching load (typically with additional reductions). If you are interested, please feel free to reach out to me directly to discuss more. This is a unique place that I have really enjoyed the past few years! Mark https://www.marksantolucito.com/

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CFP: Workshop on Hardware Acceleration of Functional and Declarative Languages
by Rob Stewart 17 Oct '23

17 Oct '23

Hi haskell-cafe, Call for participation: HAFDAL 2024 The 1st Workshop on Hardware Acceleration of Functional and Declarative Languages (HAFDAL) will be co-located with HPCA, Edinburgh on March 2nd or 3rd 2024. This workshop will bring together computer architects and programming language implementers to explore software/hardware co-designs of high level execution models. We invite two forms of participation: (1) full paper submissions for 30 minute talks, (2) 5-10 minute lightning talks about related projects and early results. For full papers, we are looking for submissions that cover the motivation, design, or real-world application of hardware technology for functional/declarative languages, their compilers and runtime systems. Submission deadline: 20 November 2023. The call for participation and all key dates are here: https://haflang.github.io/images/hafdal24_cfp.pdf The workshop's website is: https://haflang.github.io/workshops/hafdal24.html Best wishes, Rob Stewart Associate Professor Mathematical and Computer Sciences Heriot-Watt University

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