Writing high performance F# code

https://bartoszsypytkowski.com/writing-high-performance-f-code/

by pjmlp • 5 years ago

243 52 5 years ago

bartoszsypytkowski.com

airstrike2• 5 years ago

I'm a simple man – I see F# on HN, I upvote.

This great little language needs a little more love, IMHO

sgt• 5 years ago

Yes. I know literally noone who has touched it. I even know more Haskell-dabblers. But it looks very cool.

gameswithgo• 5 years ago

Olo uses it in production, if you order food online you have probably touched their f# code a bit.

jjjeii3• 5 years ago

C# gets more and more features from F#, for example you can now declare immutable records in a single line:

record Book(string Name, int publishYear)

and there are millions of jobs worldwide.

BadInformatics• 5 years ago

I used it for a couple WPF apps (of all things) a couple years back. F# is so nice for anything with a good amount of "business logic".

neurotrace• 5 years ago

I use it in production. Some of the choices they made grind my gears (I'm looking at you ordered `open`s and poor inference for records with similar shapes) but overall it's pretty nice

akra• 5 years ago

I do think it depends where you live and what ecosystem's are around there. F# to me fills a niche - i.e. in an ecosystem that uses .NET but is also more tech-savvy and willing to evaluate best tools and new approaches. That intersection of users being small shows a bit about .NET developers culture than the F# language itself (IMO only!). It happens less in the Java ecosystem and I suspect that's because Java was much slower to improve - C# isn't the best language on the platform IMO but it is improving all the time. Often reading a new C# release notes in previous roles (C# 6, 7, 9, 9) felt like reading very old F# release notes which means people don't necessarily have to take the risk to get the language endorsed in their enterprise - they just need to wait and they will eventually get something representing it (if not as generic or ideal as the F# impl).

That's more an observation I've seen on the ground in previous roles but YMMV.

pjmlp2• 5 years ago

JET, now part of Walmart.

Many UK (City area) and Swiss banks use it for data analysis.

Weebs• 5 years ago

We've been using it in production almost two years now for some backend services to serve as a source of truth for different kinds of data between various servers and applications. It's been a genuine joy for rounding up data, analyzing, and serving it. Half of that is the F# language itself, the other half is being able to use those features on a platform with great debugging + optimization tools, and a huge open source ecosystem to pull from.

dunefox2• 5 years ago

F# is a cool language that I have absolutely no use for, sadly.

chrischen• 5 years ago

You can use it + Fable to compile to JS. Assuming you had a use for JS before, now you have a use for F#.

dunefox2• 5 years ago

I have even less use for JavaScript. I mostly do NLP and DL, so it's Julia and Python for me.

ithrow• 5 years ago

Yes, sadly, the advantage of languages with big ecosystems outweigh the advantage of these languages.

I know F# can tap into the C# ecosystem but you have the mental burden of translating every example and documentation from C# to F#. In Clojure land these is pretty bad, you have to spend a lot of time understanding these extreme over-engineered over-abstracted Java libs before you can begin to use them.

skrebbel2• 5 years ago

The difference between C# and F# is smaller than the one between Java and Clojure though. Also IDE support + the fact that both languages are statically typed make it much easier to explore a C# API from F# code.

It also helps that C# has had some functional building blocks longer than Java had, which means more of the ecosystem has at least some support for passing around functions and the likes.

dgudkov• 5 years ago

Articles like that is why I keep reading HN. Excellent write-up.

Scramblejams• 5 years ago

I'm going to repost my question from a recent F# item and I hope it'll get some traction this time:

I learn a lot by reading others' code. Can anyone recommend a a project or two that is small enough for a newcomer to wrap their minds around, that also exemplifies what makes a high quality F# codebase?

jackfoxy2• 5 years ago

I've worked in F# for seven years and your question stumped me. My company's code is all private

Maybe try looking at the demo code for https://safe-stack.github.io/

I wish our online systems were #F Elmish style. Unfortunately they are TypeScript front-end, but F# server side

xupybd2• 5 years ago

Any tips for getting an F# job?

kirse• 5 years ago

Giraffe for sure:

https://github.com/giraffe-fsharp/Giraffe

As an added bonus you'll learn a very popular tool for sticking a web interface in front of your F# app.

keithnz• 5 years ago

I'd suggest having a look through https://github.com/fsprojects/awesome-fsharp and look at the high starred items (though some are not strictly F# but just something F# can use)

maybe something like suave (backend web framework).

The bigger problem I found going down the F# route is F# libraries go dead. For long term projects, far better not to use any thirdpary F# libraries and just use pretty popular third party .net libs from the C# world or the core .net lib. These days I mostly just use C#. The advantages of F# are not that big compared to just writing C# with a similar coding mindset.

airstrike2• 5 years ago

How about "Write your own Excel in 100 lines of F#"?

http://tomasp.net/blog/2018/write-your-own-excel/

https://github.com/tpetricek/elmish-spreadsheet

Gene_Parmesan• 5 years ago

This is not at all a direct answer to your question, but if you are looking for learning material on F#, https://fsharpforfunandprofit.com is kind of the default. Here's a link to a series where he builds an "enterprise tic-tac-toe" in F#: https://fsharpforfunandprofit.com/posts/enterprise-tic-tac-t...

wfhpw• 5 years ago

F# was one of the first languages I learned. Great resource!

johnisgood2• 5 years ago

Off-topic: what did you use to create those diagrams and such?

Horusiath• 5 years ago

Blog author here: as weird as it sounds, I have a prefetched Power Point template with color palette and settings, and I'm just using it for all presentations and diagrams ;)

johnisgood2• 5 years ago

Thank you, I will see what I can create using LibreOffice.

rawoke083600• 5 years ago

I wished they made the ecosystem as easy as Go to install on Linux. Last time I "tried" to get into F# (The lang looks really good). I was lost between mono and .net and the other 1000000 gazillion libraries I had to install to get a basic dev-env. After giving up half my SSD in storage, I still had env issues. :/

Barrin92• 5 years ago

Nowadays it's pretty straight forward. Just run `sudo snap install dotnet-sdk --classic`, install plugins for fsharp for vscode and you're good to go.

rattray2• 5 years ago

What's the --classic flag for? Just curious

chusk3• 5 years ago

Worth noting that snap installs aren't supported in the vscode tooling for F#. There's an open issue and I have a handle on some of the core problems, but they invalidate a ton of assumptions we have.

The safer route is to install the non-snap-based versions.

(I maintain this tooling, for what it's worth)

phillipcarter• 5 years ago

You can follow this guide for installing on your distro of choice: https://docs.microsoft.com/en-us/dotnet/core/install/linux

Unless you have a reason to only use LTS releases, install .NET 5. I suppose this doc could clarify that 3.1 is an LTS and .NET 5 is a "current" (but newer and better).

pharmakom2• 5 years ago

Same, but it’s much better now. The best combination in my experience is:

- .Net Core 5

- VS Code

- Ionide

Multicomp• 5 years ago

literally yesterday I installed the above from nothing and was trying out some F# for fun and profit code within moments...amazing how far the tooling has come from even 2 years ago

angio• 5 years ago

My experience is the opposite, with .NET Core I can manage multiple versions of the SDK with my linux package manager and not an external tool. Then in each project I specify which SDK I want to use and what dotnet tools to install.

mumblemumble4• 5 years ago

It's become a lot easer with the .NET 5 release from a couple months back.

https://devblogs.microsoft.com/dotnet/announcing-net-5-0/

3836293648• 5 years ago

Isn't F# essentially just OCaml on .NET? Wouldn't OCaml be easier to get running?

mumblemumble4• 5 years ago

In the same way that Objective-C is just C++ on OS X.

https://news.ycombinator.com/item?id=25989061

sally1620• 5 years ago

This kind of optimization actually drove me away from F#. I realized that high-performance F# is essentially imperative C# with F# syntax.

There is no place for high order functions and functional constructs in high performance F# code.

kqr• 5 years ago

essentially imperative C# with F# syntax

This sounds pretty good to me! Not to mention that once you get out of the hot path, the threshold to switch to more readable F# is very low.

pjmlp2• 5 years ago

Most of the time you won't need it, and when there is the need the tools are there.

It is no different in most languages, even C++ can look pretty ugly when going for F1 performance.

skrebbel2• 5 years ago

To be frank, I'd have upvoted you too if you'd ended your comment after "ugly".

mumblemumble4• 5 years ago

It's true of C# as well. Implementing the full suite of performance tricks precludes object-oriented techniques every bit as much as it precludes functional techniques, because the fastest possible code path is rarely going to wander through a vtable.

I suppose, though, that it's always easier to throw a baby out with the bathwater when it's someone else's baby.

pharmakom2• 5 years ago

I kind of agree... although I still think F# is a win over C#. IMO the syntax is much nicer and idiomatic F# is still pretty fast.

However, I wish the compiler would more aggressively optimise things so that I can dip into this style less often. I shouldn’t have to write the imperative stuff if the translation is mechanical!

The C++ compilers do far more work for the user, despite F# being a language much more conducive to being optimised.

It would be great if Microsoft Research could sponsor a project in this area.

Writing high performance F# code

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