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ETAPS 2016 call for participation

General haskell list - Thu, 02/11/2016 - 6:32pm
****************************************************************** CALL FOR PARTICIPATION ETAPS 2016 19th European Joint Conferences on Theory And Practice of Software Eindhoven, The Netherlands, 2-8 April 2016 ******************************************************************
Categories: Incoming News

JP Moresmau: Starting out on Android

Planet Haskell - Thu, 02/11/2016 - 10:56am
Oohhh, it's been a while since I've posted. I spent some time working on haskell-ide-engine, but then I got Haskell fatigue and decided to look at Android instead. A change is as good as a rest!

Coming from the Java world, it's not difficult to get into Android. I followed the guide on the Google site to get the basics. At first I got a bit afraid of the unholy mix of Gradle build scripts, visual layout editor, XML files and Java code, but you get over it. The IDE has some nice touches and it's good to get useful autocompletion in resources like ids and strings. I liked the warning about SDK level APIs and missing resources once I started translated my app into French.

But I have to say, when I was working on EclipseFP I often ran into IDEA fanatics that swore that IDEA was miles ahead of Eclipse. Android Studio famously moved from Eclipse to IDEA, and frankly, I don't see what the hype is about. Yes, Eclipse has some annoying bugs and idiosyncrasies. But Android Studio, at least with the default settings, as I haven't spent much time customizing it, is not such a wonderful IDE. It's slow to start up, the view layout is sometimes confusing, the font is too fine or small in places (I must be getting old, but sometimes I couldn't see that a semi colon was in fact a colon) and the warning/error markers in the gutter are way too small and nearly invisible, to the point that sometimes the build fails and I can't see where in the source is the error! Maybe there's a special "grumpy old man with failing eye sight" setting to make things bigger.

Since I believe that you learn by doing, I've developed my first app, and I'm in the process of publishing it to the App Store (so I can claim I'm a published Android developer in my CV, wink). Apart from the fact that you need to supply an icon in 2 million different sizes, which is challenging for somebody with my artistic abilities, it's a straightforward process. My app is an uninteresting workout log app (to record how much weight you supposedly lift at the gym) that's purely local (no social features, so you can't boast online about the weights you may have lifted), but hey, it's a start. The code is of course on Github.

I've also wrote a basic game using the framework presented here, and the nice asset from Kenney (see note about artistic abilities above). Nothing fancy, just a rabbit hopping over holes and getting carrots for points, but just seeing my little game running on my family's phones and tablets is nice! It's on Github too.
Categories: Offsite Blogs

Why do we want levity polymorphism?

haskell-cafe - Wed, 02/10/2016 - 11:23pm
For context, there’s currently a big thread about the type of ($), which is going to be more complicated in GHC 8.0 due to levity/runtime rep polymorphism. As I understand it, the intention is that this more complex type will be hidden unless a levity polymorphism flag is active. From my perspective, makes the question of whether this type is too complicated for beginners moot. What puzzles me is that I still don’t understand what this feature is *for*. According to [1], levity polymorphism is a more principled replacement for OpenKind, which was a bit of hack. Fine. [1] OpenKind exists because developers wanted to use ($), undefined, and error with unboxed types. That’s understandable, but it doesn’t seem worth all this effort. Surely, having to use error# instead of error when working with unboxed or unlifed types is a small thing next to all the other differences. OpenKind is also used when doing type inference, because arguments to functions mi
Categories: Offsite Discussion

Functional Jobs: Senior Functional Web Engineer at Front Row Education (Full-time)

Planet Haskell - Wed, 02/10/2016 - 8:05pm

Senior Functional Web Engineer to join fast-growing education startup transforming the way 3+ million K-8 students learn Math and English.

What you will be doing

Architect, design and develop new applications, tools and distributed systems for the Front Row ecosystem in Haskell, Flow, PostgreSQL, Ansible and many others. You will get to work on your deliverable end-to-end, from the UX to the deployment logic.

Once you're an integral part of the team you will act as Dev Lead and oversee the success of your team

Mentor and support more junior developers in the organization

Create, improve and refine workflows and processes for delivering quality software on time and without incurring debt

Work at our offices in San Francisco as part of a very small (there's literally half a dozen of us!), world-class team of engineers with a track record of rapidly delivering valuable software to millions of users.

Work closely with Front Row educators, product managers, customer support representatives and account executives to help the business move fast and efficiently through relentless automation.

Why you should join Front Row

Our mission is important to us, and we want it to be important to you as well: millions of students learn math using Front Row every month. Our early results show students improve twice as much while using Front Row than their peers who aren’t using the program.

You’ll be THE first Senior Engineer ever at Front Row, which means you’ll have an immense impact on our company, product, and culture; you’ll have a ton of autonomy and responsibility; you’ll have equity to match the weight of this role. If you're looking for an opportunity to both grow and do meaningful work, surrounded and supported by like-minded professionals, this is THE place for you.

You will be working side by side with many well known world-class personalities in the Haskell and Functional Programming community whose work you've likely used. Front Row is an active participant to the Open Source community and contributor to some of the most popular Haskell libraries.

A lot of flexibility: while we all work towards the same goals, you’ll have a lot of autonomy in what you work on. You can work from home up to one day a week, and we have a very flexible untracked vacation days policy

The company and its revenue are growing at a rocketship pace. Front Row is projected to make a massive impact on the world of education in the next few years. It's a once in a lifetime opportunity to join a small organization with great odds of becoming the Next Big Thing.

Must haves
  • You have experience doing full-stack web development. You understand HTTP, networking, databases and the world of distributed systems.
  • You have functional programming experience.
  • Extreme hustle: you’ll be solving a lot of problems you haven’t faced before without the resources and the support of a giant organization. You must thrive on getting things done, whatever the cost.
  • Soft skills: we want you to move into a leadership position, so you must be an expert communicator
  • You have led a software development team before
  • You have familiarity with a functional stack (Haskell / Clojure / Scala / OCaml etc)
  • You understand and have worked all around the stack before, from infrastructure automation all the way to the frontend
  • You're comfortable with the Behavior-Driven Development style
  • You have worked at a very small startup before: you thrive on having a lot of responsibility and little oversight
  • You have worked in small and effective Agile/XP teams before
  • You have delivered working software to large numbers of users before
  • Competitive salary
  • Generous equity option grants
  • Medical, Dental, and Vision
  • Catered lunch and dinner 4 times a week
  • Equipment budget
  • One flexible work day per week
  • Working from downtown SF, very accessible location
  • Professional yet casual work environment

Get information on how to apply for this position.

Categories: Offsite Blogs

ANN: remote-json, a JSON RPC library, released

General haskell list - Wed, 02/10/2016 - 6:04pm
Announcing a new Haskell JSON RPC library, remote-json, that uses the remote monad to bundle remote procedure calls, amortizing the cost of remote execution. There are thee bundling strategies provided: * weak (calls done one at a time), * strong (calls bundled until a reply is needed, where possible), and * applicative (an applicative functor is sent to the remote JSON RPC server). Example of use: say :: Text -> RPC () say msg = notification "say" (List [String msg]) temperature :: RPC Int temperature = method "temperature" None main :: IO () main = do let s = strongSession $ clientSendAPI "" t <- send s $ do say "Hello, " say "World!" temperature print t Blog: * <> Hackage: * <> *
Categories: Incoming News

tighter bounds for Data.Map operations (usingmin(n.m))?

haskell-cafe - Wed, 02/10/2016 - 5:29pm
Dear Cafe, I wonder if some of the resource bounds in can be improved. I do not mean "improve the implementation", but "improve the (stated) bounds". For example, I am interested in intersection(With). Bound is stated as O(n+m) (*) This is a fine worst case bound - but I certainly use this function with the implied assumption that it will not visit both trees completely - in the case that one of them is small. So, what can we say in terms of min(n,m) ? Is it linear in that parameter? Perhaps with an additional factor log(max(n,m)) ? (for looking up the keys of the smaller tree in the larger one) The paper linked from the docs has this (p 18 before 9.3) "the running time of union is better for fortuitous inputs, for example, similar sized disjoint ranges, and trees which differ greatly in size" but does not make a formal statement. This is about union, not intersection, and not hedge_union, but it's the closest this pa
Categories: Offsite Discussion

Hackage: Tarball and package description of packagemtl differ

haskell-cafe - Wed, 02/10/2016 - 4:09pm
Hi Cafe, I just wanted to install the mtl package for GHC 8.0.1-rc2, but installation failed with Setup: Encountered missing dependencies: transformers ==0.4.* Taking a look at the package description [1], it specifies build-depends: base < 6, transformers >= 0.4 && < 0.6 but the Cabal description in the tarball [2] says build-depends: base < 6, transformers == 0.4.* Strangely, if I execute $ cabal unpack mtl-2.2.1 I obtain a version with the same specification as [1]. Does anybody has an explanation for this? Regards, Björn [1]: [2]: _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe< at >
Categories: Offsite Discussion

Postdoctoral position in Functional,Constraint and/or Logic Programming

haskell-cafe - Wed, 02/10/2016 - 1:40pm
Prof. Tom Schrijvers invites applications for a postdoctoral position in the area of functional, constraint and logic programming. The position revolves around domain-specific languages (DSLs) embedded in Haskell for constraint programming. It is part of the EU project GRACeFUL whose overarching theme is tools for collective decision making. Responsibilities You will work closely with prof. Schrijvers and his PhD students at KU Leuven, as well as with the GRACeFUL project partners across Europe, in order to conduct research activities for the GRACeFUL project. For more details:
Categories: Offsite Discussion

[ANNOUNCE] GHC 8.0.1 release candidate 2

glasgow-user - Sun, 02/07/2016 - 8:13pm
Hello everyone, The GHC Team is very pleased to announce the second release candidate of the Glasgow Haskell Compiler 8.0.1 release. Source and binary distributions as well as the newly revised users guide and Haddock documentation can be found at This is the second in a series of release candidates leading up to the 8.0.1 release and fixes many of the issues reported in -rc1. These fixes include, * A re-rewrite of the pattern checker by George Karachalias. The new checker should have far more predictable performance characteristics while sacrificing minimal reasoning power. This should resolve a large number of the issues felt in -rc1. * Richard Eisenberg has been hammering out all manner of type-application- and TypeInType-related issues (#11335, #11416, #11405). There is still more work to do here, however (e.g. #11471). * Matthew Pickering has restored support for multi-clause pattern synonyms (#11367) * A latent bug
Categories: Offsite Discussion

New gtk2hs 0.12.4 release

gtk2hs - Wed, 11/21/2012 - 12:56pm

Thanks to John Lato and Duncan Coutts for the latest bugfix release! The latest packages should be buildable on GHC 7.6, and the cairo package should behave a bit nicer in ghci on Windows. Thanks to all!


Categories: Incoming News