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[ANN] New release of SBV (v7.0), now with incremental solving
by Levent Erkok 20 Jul '17

20 Jul '17

I'm pleased to announce v7.0 release of SBV, a library for integrating SMT solvers into Haskell. This release adds incremental solving capabilities to SBV: Users can now interact with the underlying solver using a typed API capturing the SMTLib language, issuing commands, getting model values, and asserting further constraints on-the-fly. The possibility of issuing multiple check-sat commands allows incremental assertion of facts, a key feature of modern constraint solving systems. Hackage: https://hackage.haskell.org/package/sbv Homepage: http://leventerkok.github.io/sbv/ Release notes: https://github.com/LeventErkok/sbv/blob/master/CHANGES.md SMTLib initiative: http://smtlib.cs.uiowa.edu/ Feedback and bug reports are most welcome! -Levent.

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How to statically link some external libraries?
by Kai Zhang 20 Jul '17

20 Jul '17

I want to produce a statically-linked executable. First I tried "-optl-static -optc-static -optl-pthrea", which statically links all external libraries. But when I ran this executable it gives me "abort (core dumped)" error. I suspect the statically-linked glibc library might be the cause. So I decide to statically link all other libraries and leave the glibc as a dynamic library. How to do this using Cabal? Should I write a custom "Setup.hs"?

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DeepSeq and random generators
by Dennis Raddle 20 Jul '17

20 Jul '17

I'm having trouble using Control.DeepSeq.force (necessary for parallel code) on a StdGen from System.Random. I don't know how to derive NFData. A standalone deriving statement, like this deriving instance NFData StdGen gets me the error "the data constructors of StdGen are not all in scope..." Is it actually possible to derive an NFData instance of StdGen, and how would I do that? Or if not possible, how can I work about this? Note: I'm going to see if I can use tf-random in this application. Maybe it will be easier. D

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any cloud computing services for running Haskell?
by Dennis Raddle 20 Jul '17

20 Jul '17

I'm thinking of using cloud computing services for running my CPU-intensive parallel Haskell code, in order to get results faster. Instead of buying a faster computer, I would take advantage of existing services. Note that my budget is small, so I need something that doesn't have a large minimum charge. I'm thinking $10 - 30 per month. Are there any cloud services like that that run Haskell? D

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"cabal quine"
by Albert Y. C. Lai 19 Jul '17

19 Jul '17

Today a few of us on IRC (freenode #haskell) discovered: The following cabal-install command cabal manpage outputs cabal-install's man page (and is mainly how cabal-install can come with a man page without carrying an extra source file). This inspires the following feature request in jest: Could "cabal quine" output its source code please? :) kthxbye

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Call for Participation: ICFP 2017
by Lindsey Kuper 19 Jul '17

19 Jul '17

[ Early registration ends 4 August. ] ===================================================================== Call for Participation ICFP 2017 22nd ACM SIGPLAN International Conference on Functional Programming and affiliated events September 3 - September 9, 2017 Oxford, UK http://icfp17.sigplan.org/ ===================================================================== ICFP provides a forum for researchers and developers to hear about the latest work on the design, implementations, principles, and uses of functional programming. The conference covers the entire spectrum of work, from practice to theory, including its peripheries. A full week dedicated to functional programming: ICFP, 2 co-hosted conferences, 1 co-hosted symposium, workshops, tutorials, programming contest results, student research competition, and mentoring workshop * Overview and affiliated events: http://icfp17.sigplan.org/home * Program: http://icfp17.sigplan.org/program/program-icfp-2017 * Accepted papers: http://icfp17.sigplan.org/track/icfp-2017-papers * Registration is available via: https://regmaster4.com/2017conf/ICFP17/register.php Early registration is due 4 August, 2016. * Programming contest, 4-7 August, 2016: http://2017.icfpcontest.org * Student Research Competition: http://icfp17.sigplan.org/track/icfp-2017-Student-Research-Competition * Follow @icfp_conference on twitter for the latest news: http://twitter.com/icfp_conference There are several events affiliated with ICFP: Sunday, September 3 Workshop on Higher-order Programming with Effects Workshop on Type-Driven Development Scheme and Functional Programming Workshop Programming Languages Mentoring Workshop ICFP Tutorials Monday, September 4 – Wednesday, September 6 ICFP FSCD - Days 1-3 Thursday, September 7 Haskell Symposium – Day 1 ML Family Workshop Workshop on Functional High-Performance Computing Commercial Users of Functional Programming – Day 1 FSCD - Day 4 Friday, September 8 Haskell Symposium – Day 2 OCaml Workshop Erlang Workshop Commercial Users of Functional Programming – Day 2 Saturday, September 9 Commercial Users of Functional Programming – Day 3 Haskell Implementors Workshop Functional Art, Music, Modeling and Design Conference Organizers: General Chair: Jeremy Gibbons (University of Oxford, UK) Program Chair: Mark Jones (Portland State University, USA) Artifact Evaluation Co-Chair: Matthew Flatt (University of Utah, USA) Artifact Evaluation Co-Chair: Ryan R. Newton (Indiana University, USA) Industrial Relations Chair: Ryan Trinkle (Obsidian Systems LLC, USA) PLMW Co-Chair: Neelakantan R. Krishnawami (University of Cambridge, UK) PLMW Co-Chair: Dan Licata (Wesleyan University, USA) PLMW Co-Chair: Brigitte Pientka (McGill University, Canada) Programming Contest Organiser: Sam Lindley (University of Edinburgh, UK) Publicity and Web Chair: Lindsey Kuper (Intel Labs, USA) Student Research Competition Chair: Ilya Sergey (University College London, UK) Student Volunteer Co-Captain: Yosuke Fukuda (Kyoto University, Japan) Student Volunteer Co-Captain: Yuki Nishida (Kyoto University, Japan) Student Volunteer Co-Captain: Jakub Zalewski (University of Edinburgh, UK) Video Chair: Jose Calderon (Galois, Inc., USA) Workshops Co-Chair: Andres Löh (Well-Typed LLP, UK) Workshops Co-Chair: David Christiansen (Indiana University, USA) Sponsors and industrial partners: Platinum partners Ahrefs Jane Street Capital Gold partners Bloomberg X Silver partners Galois Oracle Bronze partners Obsidian Systems Portland State University Well-Typed

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Is there something new in GHCi?
by Francisco Vieira de Souza 18 Jul '17

18 Jul '17

I´m using GHCi for Windows and I found sometrhing new. Mainly, there is no way for using GHC tooI for making a executable program. I had been doing all that is written in the page of Haskell and the same thing. I think that is something wrong in this new way of installation of GHC. Someone can help me in this case? Thanks in advance! Vieira -- "Embora ninguém possa voltar atrás e fazer um novo começo, qualquer um pode começar agora e fazer um novo fim". (Chico Xavier)

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Fwd: Memoization in Type Calculation
by Dmitry Olshansky 18 Jul '17

18 Jul '17

Rahul, thanks! It is really simple! 2017-07-17 21:33 GMT+03:00 Rahul Muttineni <rahulmutt(a)gmail.com>: > Hi Dmitry, > > You can effectively think of the type-level language of Haskell as a > strict functional language with almost no syntactic sugar, and recursion is > the *only* way of getting the behaviour of a loop. The best you can do to > improve the performance of that type family is to write it in > tail-recursive form using a helper function and which will make the type > family reduction look more linear vs a tree like it is now and make it > easier for the type checker to quickly spit out the result. > > type family Fib (n::Nat) :: Nat where > Fib n = GoFib 0 1 n > > type family GoFib (a :: Nat) (b :: Nat) (n :: Nat) where > GoFib a _ 0 = a > GoFib a b n = GoFib b (a + b) (n - 1) > > Hope that helps, > Rahul > > On Mon, Jul 17, 2017 at 11:19 AM, Dmitry Olshansky <olshanskydr(a)gmail.com> > wrote: > >> Hello, cafe! >> >> I wonder is there some possibility to get Memoization in Type Calculation >> (e.g. in closed Type Families)? >> >> Can we make something more efficient for famous Fib function then >> >> type family Fib (n::Nat) :: Nat where >> Fib 1 = 1 >> Fib 2 = 1 >> Fib n = Fib (n-1) + Fib (n-2) >> >> This Fib has obviously exponential calculation time and we need some >> memoization. >> >> If it is impossible right now, maybe there is a ticket for this? It seems >> to me very important things, no? >> >> Probably in this case we can write TypeChecker Plugin, but it looks like >> the common problem. >> >> Best regards, >> Dmitry >> >> >> >> >> _______________________________________________ >> Haskell-Cafe mailing list >> To (un)subscribe, modify options or view archives go to: >> http://mail.haskell.org/cgi-bin/mailman/listinfo/haskell-cafe >> Only members subscribed via the mailman list are allowed to post. >> > > > > -- > Rahul Muttineni >

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Memoization in Type Calculation
by Dmitry Olshansky 18 Jul '17

18 Jul '17

Hello, cafe! I wonder is there some possibility to get Memoization in Type Calculation (e.g. in closed Type Families)? Can we make something more efficient for famous Fib function then type family Fib (n::Nat) :: Nat where Fib 1 = 1 Fib 2 = 1 Fib n = Fib (n-1) + Fib (n-2) This Fib has obviously exponential calculation time and we need some memoization. If it is impossible right now, maybe there is a ticket for this? It seems to me very important things, no? Probably in this case we can write TypeChecker Plugin, but it looks like the common problem. Best regards, Dmitry

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[Hiring] NStack is hiring Haskellers in London (onsite / remote)
by Mandeep Gill 18 Jul '17

18 Jul '17

NStack (www.nstack.com / www.github.com/nstack/nstack) lets data scientists and analysts to do sophisticated data work in the cloud without a team of engineers. To accomplish this, we’re a building a platform for composable, data-driven microservices, using a mixture of Haskell and Linux systems tech (including Kubernetes, systemd, and local IPC) with some typed DSLs, systems code, and distributed systems thrown in - think Bash-piping for distributed, containerised microservices. Our aim is to bring many of the ideas from functional programming, such as typed APIs and composition to the analytics space. We have an early demo of the product available, see www.github.com/nstack/nstack to get started and https://demo.nstack.com (very early demo, built using GHCJS - see [1]), and are currently in trials with several enterprises. We’re looking for talented programmers experienced using typed functional languages with preferably some Linux/Unix systems knowledge. It’s a challenging role, working on hard problems, and offers the chance to work with a top technical team and shape a company and product from an early stage. NStack is funded by top-tier investors from the West Coast, the founders are both technical and ex-YC / academia, and our team is lucky enough to include world-class talent for the problem we're solving. Salaries are competitive and include generous stock options. We're generally hiring onsite, however several of us work across Europe and we welcome remote applications within suitable timezones. Unfortunately we can not sponsor work visas. We're a team of 10, including 5 full-time Haskellers, and are looking at a range of positions and experience levels - whether you’ve just left uni or been hacking for 20 years, so if you’re interested please get in touch. Any questions please email direct or take a look at https://angellist.com/nstack/jobs Cheers, Mandeep [1] log in using `user-id` = `be56de22d8444786ae3231953b2cf4b1` and `secret-key` = `8d245132f0a9402d9284cf2e0a280391`

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