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F# Not just for finance

182 points| markfsharp | 9 years ago |fsharp.tv

134 comments

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gmantom|9 years ago

While I think F# is a great programming language. The article missed some good uses of it.

Specifically the article missed one of largest F# deployment, in production, in the world at this point. We use F# at Jet.com and it powers every part of our core business from our dynamic pricing algorithm to search and analytics.

Over 4 million customers already on jet and over 2200 cores on azure all running F# code.

louthy|9 years ago

> Over 4 million customers already on jet and over 2200 cores

That sounds like a lot of cores for such a small data-set. Are you able to expand a little more on why you need so much computing resource?

cm3|9 years ago

What concurrency models do you employ to saturate all cores, and how's GC behavior?

insulanian|9 years ago

There is an interesting article about rewriting C# project in F#, with impressive results: http://simontylercousins.net/does-the-language-you-use-make-...

wrsh07|9 years ago

This is a really great case study, but I can't help but think some of the improvement comes from it being the second attempt at the project.

I'd really like to see some case studies going the other way: F# --> C# [or C++].

At the least, you could do C# --> C# [ie complete rewrite]. Any time you do a rewrite with more knowledge of what worked and what didn't, you'll have a better system.

So ultimately, the essay [like most] leaves the question: Is F# better? Or is it just that complete rewrites can provide substantial improvement?

hvs|9 years ago

I was an early adopter of F# (1.0) and promoted it pretty heavily in my previous job. We used it for some of our prediction code.

I've since left and move to the Linux world, but have become more involved with using OCaml. Both are great languages (probably my favorites) and that's after investigating Haskell for a while. F#/OCaml's ability to easily move between functional/procedural/OO worlds makes it super flexible.

gnuvince|9 years ago

> F#/OCaml's ability to easily move between functional/procedural/OO worlds makes it super flexible.

When I wrote the reference compiler for an intro to compiler class in OCaml, some of the teams who used Haskell asked me about my choice; I said that while most of the compiler was written in a nice FP style, it was nice to have imperative constructs in a few places to follow the techniques from a textbook without having to adapt them and making sure that I haven't changed the complexity.

edgyswingset|9 years ago

>I've since left and move to the Linux world, but have become more involved with using OCaml.

Have you taken a look at F# on .NET Core? It's still in alpha, but aside from some of the FSharp.Core libraries you can write a lot of code with it.

rcarmo|9 years ago

I liked tinkering with F# on VS Code with Ionide (https://marketplace.visualstudio.com/items?itemName=Ionide.I...), but would love to hear from folk doing F#/OCaml as to their toolsets.

louthy|9 years ago

We use it for satellite projects around our core C# app (the only reason the core isn't F# is legacy, so I created a C# library to get as close as possible when updating/refactoring [1]).

The toolset is pretty boring/standard though: VS2015 + TeamCity + in-house Nuget + Gitlab

[1] https://github.com/louthy/language-ext/

ZenoArrow|9 years ago

As far as I'm aware, the most popular F# tools for writing code are (from most to least popular): Visual Studio, Ionide (either using Atom or VS Code) and Emacs. I haven't seen that many people coding in F# using anything else, but I'm sure you'd find a few people using the usual suspects (Vim, Sublime Text, etc...).

Keats|9 years ago

Is anyone using F# on Linux? How's the experience?

insulanian|9 years ago

I'm running it in prod since last year and from the runtime perspective there are no issues.

Tooling is what sucks. MonoDevelop F# support is very unreliable. Basic refactoring, like rename, don't work correctly every time and I had to literally do git reset few times, after renaming, as it screw up multiple files.

Also, editor often has visual glitches where letters get corrupted and I have to reopen the file to get it back to normal. Not something I expect from such a long time maintained application. However, it looks like Xamarin Studio 6.0 will be much better.

Alternative is Visual Studio Code with Ionide plugin, but I didn't use that beyond trying it once. Hopefully someone else can comment.

Edit: typos

monads|9 years ago

After my experience, it run smoothly on Linux. I followed the guide at http://www.monodevelop.com/ to install mono, then F#; monodevelop is also a good IDE but personally I use spacemacs with F# layer.

e_tolmachev|9 years ago

We have several solutions developed in F# over the past year or so that run exclusively on Linux. Mono 4.x has made it an a viable choice for running in production, but the dev experience is still lacking. We develop mostly on Windows with F# power tools plugin. You can find our open-source stuff at https://github.com/Prolucid

klibertp|9 years ago

It works, although from what I recall the installation wasn't that easy. I think I had to checkout a specific tagged commit instead of the newest master, because the latter had a broken build. Probably works now, it was years ago :)

djahfskl|9 years ago

Im using it on linux, its pretty good in my opinion, im still learning, but packet and stuff like that seems to work fine. Im using it with emacs, so i dont really know how you will fare with other editors.

ProfChronos|9 years ago

Just tried F# on https://www.codingame.com/games/puzzles Don't really see the use case for me, but fun to try smthg new => "one new language a day keeps the boredom away"

NovelSpinGames|9 years ago

That's an awesome website! I made it through the first three puzzles using F#. It's too bad that there's nothing like IntelliSense there, but you can use Visual Studio or www.tryfsharp.org for typing and CodinGame for testing. It looks neat, but might not be the best for learning a new language. You can see some clever solutions after solving a puzzle at least. How familiar are you with F# and functional programming?

bmay|9 years ago

What are your thoughts on CodinGame?

shitgoose|9 years ago

I came across F# a couple of months ago. Very nice language! Short, expressive, no noise like declaring vars/types that can be easily inferred at compile time. |> is amazing. Tuples. 'match with'. Took a couple of weeks to get over the hump, but I never looked back since. Work related stuff is still C#, but tooling, prototyping etc I do in F# now. Highly recommend. Also made me to rediscover glorious past of OCaml/ML that went over my head at the time (like most things).

melling|9 years ago

I enjoyed reading this retrospective about someone converting 30,000 lines of Python to OCaml.

http://roscidus.com/blog/blog/2014/06/06/python-to-ocaml-ret...

OCaml and F# are quite close.

vessenes|9 years ago

I only know Go well enough to comment on his comments, but he did not do a good job testing and reporting on it in his posts, ignoring basic recommendations about safety taught to all beginners. (Ignores err responses from functions and then later complains that things fail later, most particularly).

I would be cautious about drawing too many conclusions about languages he didn't end up picking; clearly he knows OCaml and Python well.

dintech|9 years ago

I'm quite sure KDB pays more.

pmarreck|9 years ago

I want to suggest looking at a language like Erlang/Elixir that didn't start out from corporate self-interest (i.e., was open-source from the get-go) but a rising functional tide floats all boats. (And besides, Elixir "borrowed" a few good ideas from F#.)

I've had nothing but good experiences during my forays into functional langs. Here's to a more functional, immutable, easily-concurrent, easily-unit-tested future

eggy|9 years ago

As commented by others, F# was part of Microsoft Research, and not taken up by MS or other corporations when it was started.

Erlang started out in Ericsson, a corporation. Elixir and LFE (Lisp Flavored Erlang) started out opensource and are still opensource.

The term 'corporate self-interest' seems misplaced here, with the parenthetical remark turning it into the antonym of 'open-source'. The term proprietary, commercial or close-sourced seem more neutral and correct.

Erlang started inhouse at Ericsson, like F# did at MS Research, except it was for a company's immediate business needs or 'self-interest' to program their telecomm switches.

Elixir grew out of one person's frustration with Ruby's concurrency (Jose Valim), and a desire to have what Erlang offered him along with the BEAM VM and OTP. It has Ruby-like syntax, Jose is a popular Rubyist, and great tooling along with some other functional structures Jose added that he thought were missing in Erlang. [2]

Pony is an OO, actor-based, open source language, yet it has a lot of corporate pickup from fintech and others, and it seems to be getting ready to shove Erlang/Elixir/LFE aside on concurrency and speed. It has fully-concurrent garbage collection that doesn't use the "poison pill" message approach to kill all actors.

The creator of Pony, Sylvan Clebsch, has one foot in academia, and the other in business. He has worked on fintech, milsims, and games. [3]

[1] http://www.ponylang.org/

[2] https://www.sitepoint.com/an-interview-with-elixir-creator-j...

[3] http://www.curry-on.org/2015/sessions/pony-making-it-easier-...

strmpnk|9 years ago

F# comes from Microsoft Research and was notoriously ignored by the corporate side for years (and still is to some extent). So I'm not sure F# has really ever been a project of Microsoft corporate interest, and now there is the F# Foundation which has many non-MSFT people and companies involved.

While I like Erlang a lot, I'd say that Ericsson still has quite a bit of corporate control and interest. It's not always a bad thing to have companies involved in the success and advancement of technology.

jackmott|9 years ago

If you wanted something like F# that isn't backed by Microsoft, I would suggest OCaml, which is what F# is.

insulanian|9 years ago

I've looked at it and it looks nice indeed. Having BEAM underneath is a big plus.

However, dynamic typing turned me off. Whole my life I'm working with statically typed languages and heavilly rellying on compiler / type system to catch my mistakes / guide my design. Hard to give up on that.

gtycomb|9 years ago

Is porting OCaml code to F# on Unix straight forward? Is there something similar to the Opam package manager in F#? Thanks for your thoughts.

strmpnk|9 years ago

F# is similar but if you're using features like polymorphic variants, functors, or first class modules, it might take more effort. In terms of package management, I'd check out paket. It wraps up the otherwise very quirky nuget system that .Net uses and also supports things like source dependencies.

haddr|9 years ago

Where is R on those charts on functional languages?

mamcx|9 years ago

Where are the best place to find that F# jobs? I will love to work on it (+17 developing but this years I have picked F#)

manish_gill|9 years ago

This was a bit of a surprise to me. Is there a disproportionate amount of people in Finance using F# compared to other technologies? Any particular reason for that if the answer is yes?

bwooceli|9 years ago

A high price tag for a niche language (purely defined by "popularity") is hardly surprising, simple question of supply and demand.

bad_user|9 years ago

I think the article is spammy and has a clickbait title. Unfortunately reading and addressing the actual article on Hacker News is old-fashioned.

StackOverflow surveys, while interesting, are probably meaningless because they suffer from selection bias. Even so, I would guess that F# developers are very well paid, like other developers of FP languages, but it's probably not because they work with F#. The causality is likely reversed - good developers that tend to be well paid are also the kind of people naturally interested in expanding their skill set, hence interested in FP languages.

Nothing screams spam more than usage of a hot keyword like "functional programming" while leaving hints that you don't understand what you're talking about. I would expect an article that reads like a marketing brochure to at least make a short attempt at explaining what functional programming is. If you copy/paste testimonials from fsharp.org/testimonials, you could also copy/paste from Wikipedia. But then, their own course named "Functional Programming" doesn't seem to have anything to do with actual functional programming: https://fsharp.tv/courses/functional-programming/

insulanian|9 years ago

> their own course named "Functional Programming" doesn't seem to have anything to do with actual functional programming

Why do you think so?

jackmott|9 years ago

F# was also voted most LOVED language in the F# survey.

ZenoArrow|9 years ago

Functional programming is a broad term that at its core describes languages that allow you to pass functions around as values to other functions.

In other words, when using a function the parameters of that function can be defined as other functions instead of needing to be precalculated variables or constants.

That's basically all that links functional programming languages, all other language design decisions can vary.

smoothdeveloper|9 years ago

I think the title can be alleged mostly to the misconception which is prevalent at Microsoft since F# was introduced as a commercial product (before it used to be a Microsoft Research product).

Maybe you are unaware of that?

F# is a pretty good general purpose programming language and that is what the title and article tries to promote (albeit it doesn't give enough and diversified examples).

F# is also a reasonably easy programming language which puts emphasis first on "functional programming" (which you frame as hot keyword, I doubt the language was made to fill a hot keyword).

I don't know about the for pay contents of fsharp.tv, but I gather they might be introductory and try to bring understanding of "functional programming" aspects to an audience which isn't versed in it, it is sure good for them if "functional programming" is a hot keyword and people are looking for training material to pickup that language, but I wouldn't dismiss that as being spammy.

Chill out dude :)

spazzpp2|9 years ago

Long time no see, #F.

hackaflocka|9 years ago

> F# came out as the single most highly paid tech worldwide and is amongst the third top paying techs in the US

Wouldn't the latter be implied by the former? Or am I missing something?

jboynyc|9 years ago

That is confusing/questionable wording, but it can still be logically consistent. Here's an analogy: Football (soccer) is the most popular sport worldwide, but it is not among the top sports in the U.S.

lucozade|9 years ago

Not necessarily. Bear in mind this based on survey results from Stack Overflow and the sizes for some of the categories are quite small.

For example. Dart is the second highest paid language globally but doesn't even figure in the top paying US (maybe because too few US Dart devs responded).

mariusmg|9 years ago

Programming languages are hyped now worse than cars : "From code to colossal: Waagner-Biro recently used F# to construct the dome of the Louvre Abu Dhabi museum" They used X programming language to build the dome of a museum ? Wowwww...

It's sad.

nickpeterson|9 years ago

Construct is probably a poor choice of words. Design would be more accurate.