- Haskell-Cafe - Haskell.org

JOB OPPORTUNITY_ Jr. Functional Software Developer
by CREATE-NET Jobs 02 Sep '15

02 Sep '15

CREATE-NET is seeking a motivated Junior Functional Software Developer. You will be part our innovation IT team based in Trento, Italy, and will be contributing to the development and testing of our specialized software products which support the workflow related to scientific content organization. *Technical skills* ● Experience with one or more functional programming languages. Haskell and Common Lisp are preferable. ● Experience with web technologies: Javascript, HTML5, CSS, AJAX, JSON APIs, web services, responsive web design. ● Optional knowledge of either Node.js, Ruby on Rails, PHP, Java is considered a plus ● Experience with relational DBMSs (PostgreSQL) ● Experience with distributed version control systems (Git) ● Familiarity in working with GNU/Linux environments (RHEL, Ubuntu, etc.) *Specific job responsibilities will include* ● Contributing to the maintenance and the improvement of our content management platforms and applications; ● Developing new solutions for software integration ● Interacting with the project responsible and the user community to determine requirements and communicating with the support team to handle issues or new features requests. *Organizational skills* ● Autonomous thinking and problem solving skills; ● Prioritization, time management skills and capability to adapt to dynamic environments; ● Ability to work hands-on and with little supervision; ● Ability to timely deliver your work as per an agreed roadmap; ● Attitude to collaborative working; Applicants should have Bachelor’s degree (or equivalent experience) in computing or other related disciplines and a proven experience in software development. They should be enthusiastic about web applications technologies and willing to expand their knowledge and skills on other technologies too. Please include any Github/Bitbucket or otherwise links to open-source contributions you have made. *How to Apply: *Please send your resume/CV in English to careers(a)create-net.org, specifying in the email subject: “FUNCTIONAL SOFTWARE DEVELOPER -HC”. Only applications submitted in English will be taken into consideration. *Important:* Due to Italian Privacy Protection Law n.196/03 any resume not mentioning explicitly the following wording: “I authorize the use of my personal data in accordance with Italian Privacy Protection Law (30/06/2003, n.196/03)” will be automatically deleted from our database and consequently not taken into consideration. *Languages:* Good command of the English language (written and spoken) is essential. Knowledge of the Italian language both spoken and written is not required, but can be helpful. *Working Place*: Povo (Trento), Italy

1 0

Fwd: How to combine simulations
by David Sorokin 02 Sep '15

02 Sep '15

Hi all, I forgot to click on ReplyAll. I thought that my answer could be interested to others as well. Therefore, I resend the letter to Haskell Cafe. Thanks, David ---------- Forwarded message ---------- From: David Sorokin <david.sorokin(a)gmail.com> Date: Wed, Sep 2, 2015 at 9:39 AM Subject: Re: [Haskell-cafe] How to combine simulations To: martin <martin.drautzburg(a)web.de> Hi Martin, Nevertheless, regarding Aivika, did you look at the Signal type (inspired by the IObservable interface of .NET)? This type is quite composable. If I understood you correctly, the Signal is what you call Event. Moreover, if you need a mutable state, then you could use the Ref reference and its signal refChanged. For example, the reference could be used to decide whether to emit a signal based on the intermediate state. Furthermore, if you want to build a computation with linear-looking signal processing then you could use the Process monad (inspired by the Async workflow of F#) and the processAwait function that suspends the current discontinuous process waiting for a signal to come. I hope it helps. In case of need, these ideas can be re-implemented. Thanks, David On Mon, Aug 31, 2015 at 7:48 PM, martin <martin.drautzburg(a)web.de> wrote: > Hello all, > > I've been trying hard to come up with an idea how to build a DES from > smaller parts. So far, I came to the conclusion, > that somewhere there must be an operation which takes an Event and maybe > emits an Event (and appends to a log and > updates some state). Those Events whould come from and go to the > "environment" the simulation runs in. > > My mental model is two billiard tables, which are connected through a hole > in the cushion and which each have a player. > When I look at one such table, it would have to respond to Events from its > player and from the other table and it would > send events to its player ("all balls at rest") and to the other table. > > If I add the other table and the two players then the combined simulation > would not emit any events at all and it would > not respond to any events except maybe as START event. It would only > depend on its initial state. > > But if I add only the player, but not the other table, it would still send > events to the other table and respond to > events from that other table. > > My problem is the type of Events. I could create a type which encompasses > all possible events, but that violates the > idea of composablitly. Somehow I would need to be able to take a system > which accepts "player events" and "other table > events", compose it with an other table and end up with a system which > only accepts "player events" but no more "other > table events" and similarly for the emitted events. And I don't quite know > how to do this. > > Hope this makes some sense. > > Any pointers (which go beyond "aivika has a simulation component") would > also be much appreciated. > _______________________________________________ > Haskell-Cafe mailing list > Haskell-Cafe(a)haskell.org > http://mail.haskell.org/cgi-bin/mailman/listinfo/haskell-cafe >

1 0

How to combine simulations
by martin 01 Sep '15

01 Sep '15

Hello all, I've been trying hard to come up with an idea how to build a DES from smaller parts. So far, I came to the conclusion, that somewhere there must be an operation which takes an Event and maybe emits an Event (and appends to a log and updates some state). Those Events whould come from and go to the "environment" the simulation runs in. My mental model is two billiard tables, which are connected through a hole in the cushion and which each have a player. When I look at one such table, it would have to respond to Events from its player and from the other table and it would send events to its player ("all balls at rest") and to the other table. If I add the other table and the two players then the combined simulation would not emit any events at all and it would not respond to any events except maybe as START event. It would only depend on its initial state. But if I add only the player, but not the other table, it would still send events to the other table and respond to events from that other table. My problem is the type of Events. I could create a type which encompasses all possible events, but that violates the idea of composablitly. Somehow I would need to be able to take a system which accepts "player events" and "other table events", compose it with an other table and end up with a system which only accepts "player events" but no more "other table events" and similarly for the emitted events. And I don't quite know how to do this. Hope this makes some sense. Any pointers (which go beyond "aivika has a simulation component") would also be much appreciated.

2 1

Backing up ghc version, just for one sandbox?
by David Banas 01 Sep '15

01 Sep '15

Hi all, Is it possible to back up the ghc version, just for a single sandbox? Thanks, -db

1 0

Compiling non-registered packages into a sandbox?
by David Banas 01 Sep '15

01 Sep '15

Hi all, How do I compile a non-Hackage registered package into a local sandbox? Let’s say I have: /proj_dir/ - .cabal-sandbox/ - cabal.sandbox.config - dep_pkg/ - dep_pkg.cabal - Setup.lhs - … I’d like to compile the dep_pkg package into my proj_dir sandbox; can I do this, if dep_pkg is NOT registered with Hackage? If so, how? Thanks, -db

2 1

New Functional Programming Job Opportunities
by Functional Jobs 01 Sep '15

01 Sep '15

Here are some functional programming job opportunities that were posted recently: Full Stack Haskell Software Engineer at Linkqlo Inc http://functionaljobs.com/jobs/8859-full-stack-haskell-software-engineer-at… Cheers, Sean Murphy FunctionalJobs.com

1 0

Thread-safe GHC
by Corentin Dupont 31 Aug '15

31 Aug '15

Hello, I am wondering if GHC itself is thread-safe. I am using Hint, and it reports that GHC is not thread-safe, and that I can't safely run two instances of the interpreter simultaneously. Is that still the case? Thanks! Corentin ---------- Forwarded message ---------- From: Daniel Gorín <jcpetruzza(a)gmail.com> Date: Thu, Aug 27, 2015 at 5:09 PM Subject: Re: Thread-safe Hint To: Corentin Dupont <corentin.dupont(a)gmail.com> Hi Corentin, sorry for the late reply. Until relatively recently, the problem was still on. But I too remember seeing something related to this issue being fixed (iirc, the problem was the runtime linker, which used global state), so perhaps it is already fixed in 7.10. If you can verify this, it shouldn’t be hard to show the error message only on old versions of ghc. I’ll be away for a couple of weeks, but if you want to look into this and send a patch, I’ll merge it when I return. Cheers, Daniel > On 24 Aug 2015, at 10:43 am, Corentin Dupont <corentin.dupont(a)gmail.com> wrote: > > Hello Daniel, > I noticed the following message in Hint: > This version of GHC is not thread-safe,can't safely run two instances of the interpreter simultaneously. > > Is it still the case with recent versions of GHC? > It would be neat to be able to launch several instances of the interpreter. In my game Nomyx I have several "match-up" going on and having one instance of the interpreter would be nicer. Otherwise I am obliged to reset the interpret each time I want to interpret something, which is time consuming (2-3 seconds). > > Thanks, > C

1 0

Re: [Haskell-cafe] Discussion: The CLOEXEC problem
by Donn Cave 31 Aug '15

31 Aug '15

Quoth David Turner <dave.c.turner(a)gmail.com>, > Could you be a bit more specific? Which bits of pre-existing software > didn't have a FD_CLOEXEC bit and would be broken by this proposal? Well, of course to be precise, the bit's always there, it's just normally not set - that's the normal environment that anything written up to now would expect. And of course, anything that depends on a GHC-opened file to stay open over an exec would be broken. I can't enumerate the software that meets that criterion. > Since Python recently decided to go through this exact transition, their > experience should be instructive. Do you know if there was negative fallout > from PEP 0466? I gave up on Python a long time ago and don't follow what goes on. If recently means less than a decade or so, though, it's not much to go on. If the problem addressed by the O_CLOEXEC proposal is obscure, the problems it may create are even more so - I'll certainly concede that - and it could take a lot of experience before those problems would be well known enough to show up if you went looking for them. > When thinking about FDs from outside the Haskell runtime (whether inherited > or simply opened in an external library), can you give an example of a case > where such a FD causes a problem if inherited and yet cannot be set as > FD_CLOEXEC at source? Sorry, I'm confused here. Files opened within GHC and externally have equal potential to work as intended or to cause problems, it seems to me. If we infer from the proposal that GHC-opened files with CLOEXEC unset may cause a problem, then it follows that other files with CLOEXEC unset also may cause the same problem. The proposal addresses only the former, and not the latter, and only for normal files - while the ordinary solution, as implemented in UNIX popen(3), deals with all - pipes, sockets, etc. Donn

6 10

Idiomatic way to parse bytecodes
by Gautier DI FOLCO 31 Aug '15

31 Aug '15

Hello all, I have some bytecodes to parse and I look for the most idiomatic way to do it. It's mostly JVM Bytecode, long story short, I have some embedded JVM Bytecodes: * one part is specification-defined, from 0x00 to 0xB8, differ from the regular JVM Bytecode * and the other part is proprietary and changes often I have two main goals: * print the signification of each bytecodes (a more explicit one than the hexadecimal value of the bytecode) * Do some analysis on it, spot patterns, apply markov model on it and so on. The issue with JVM Bytecode in general is that each bytecode hasn't been made equal. Some of them requires parameters, some of them modify the length of the next bytecode, etc. I'm not looking for a way to parse bytecode quickly, or for a library doing it for me. I look for a simple/composable/idiomatic way to do it. So if you have any thoughts, papers, articles or even code snippets (part of a library of not) that is done in the Haskell-way, please, share it :) Thanks in advance for your help.

4 4

Haskell Engineer Needed for Machine Learning Startup
by Charles Weitzer 31 Aug '15

31 Aug '15

Voleon Capital Management LP is a startup quantitative hedge fund located in Berkeley, California. We would like to hire a senior software engineer with strong functional programming experience as soon as possible. Voleon's founders previously worked together at one of the most successful quantitative hedge funds in the world. Our CEO has a PhD in Computer Science from Stanford and has been CEO and founder of a successful Internet infrastructure startup. Our Chief Investment Officer has a PhD in Statistics from Berkeley. Voleon's team includes PhD's from leading departments in statistics, computer science, and mathematics. We have made several unpublished advances in the field of machine learning and in other areas as well. Here is our formal job description: ********************************************************** * Senior Software Engineer * Technology-driven investment firm employing cutting-edge statistical machine learning techniques seeks an exceptionally capable software engineer. You will architect and implement new production trading systems, machine learning infrastructure, data integration pipelines, and large-scale storage systems. The firm researches and deploys systematic trading strategies designed to generate attractive returns without being dependent on the performance of the overall market. Join a team of under 30 people that includes a Berkeley statistics professor as well as over ten PhD's from Berkeley, Chicago, CMU, MIT, Princeton, Stanford, and UCLA, led by the founder and CEO of a successful Internet infrastructure technology firm. The firm's offices are walking distance from BART and the UC Berkeley campus in downtown Berkeley, California. We have a casual and collegial office environment, catered lunches, and competitive benefits packages. We seek candidates with a proven track record of writing correct, well-designed software, solving hard problems, and delivering complex projects on time. You should preferably have experience designing and implementing fault-tolerant distributed systems. Experience with building large-scale data infrastructure, stream processing systems, or latency-sensitive programs is a bonus. We are growing rapidly. Willingness to take initiative and a gritty determination to productize are essential. Required experience: - strong experience developing in a functional programming environment (Haskell, Erlang, others). - developing with C/C++/Python/Go in a Linux environment with a focus on performance, concurrency, and correctness. - working in TCP/IP networking, multi-threading, and server development. - working with common Internet protocols (IP, TCP/UDP, SSL/TLS, HTTP, SNMP, etc.). - architecting and designing highly available systems. - architecting and designing large-scale data management infrastructure. - working in large codebases and building modular, manageable code. Preferred experience.: - debugging and performance profiling, including the use of tools such as strace, valgrind, gdb, tcpdump, etc. - working with build and test automation tools. - working with well-defined change management processes. - diagnosing RDBMS performance problems, exploiting indexing, using EXPLAIN PLAN, optimizing at the code layer, etc. - working with messaging queues (RabbitMQ, Redis, etc.) as well as distributed caching systems. Interest in financial applications is essential, but experience in finance is not a primary factor in our hiring. Benefits and compensation are highly competitive. ********************************************************** The above job description is just a starting point in terms of possible duties and seniority. We can be very flexible for the right person. If you are interested or if you know of anyone who might be interested, let us know the best way to get in touch and we can discuss details. Thank you, Charles Weitzer Senior Recruiter Voleon Capital Management LP Charles(a)Voleon.com<mailto:Charles@Voleon.com> Office: 510.704.9870 x 7012 Mobile: (510) 558-9182 www.Voleon.com<http://www.voleon.com/>

1 0