.Net Foundation On .NET, 10 May 2018

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From YouTube: What's new in F#

Description

F# is a functional programming language that runs on .NET. It has a great community behind it, and now comes included with .NET Core.
In this episode, Phillip Carter (@_cartermp) joins Rich (@runfaster2000) to talk about what is new for the F# language. Phillip talks about where F# fits in the family of .NET languages and how it compares to C#. He also gives us a demo of the tooling in Visual Studio, and talks to us about how to get started.

00:47 - Why would someone pick F#
02:28 - How does F# compare to other families of languages
03:40 - Is F# more of an academic language?
04:44 - How approachable is F#
05:50 - What's new in the Visual Studio tooling for $F?
11:00 - What are F# type providers?
23:53 - How do you get setup with F# in Visual Studio?

Check out these links below to learn more about the F# language.

F# Documentation: https://docs.microsoft.com/en-us/dotnet/fsharp/?WT.mc_id=ondotnet-channel9-cephilli
F# on Azure: https://docs.microsoft.com/en-us/dotnet/fsharp/using-fsharp-on-azure/?WT.mc_id=ondotnet-channel9-cephilli
Ionide, Visual Studio Code Extension for F#: http://ionide.io/
fsharpConf Videos: https://channel9.msdn.com/Events/FSharp-Events/fsharpConf-2018
Create a Free Account (Azure): https://aka.ms/azft-net

A

On today's episode of the on .net show we're going to be learning about. What's new, with f# from phillip carter. check it out.

A

Hi! welcome to another episode of on .net..

A

Today we're going to learn about what's new in f# from phillip carter.

A

hey? hey,, how it's going. not too bad. yourself? good, good.. I actually used to watch the show back when I was growing up, because we're different ages called welcome back carter.. Do you know that show?.

B

No,, I don't. I'm afraid I'm too young.

A

Okay. yeah, you should watch that., okay. so, you're, the f# language and tools, pm?.

A

Yes. yes., so how about we start with some basics.?

A

We've got all these languages that microsoft chips kind of like how does f# fit into that.

B

And also, why would someone pick f#.

A

Yeah, totally. so well,.

B

Have it up here in a little website.

A

B

Handy dandy, little site., it's an open source cross platform, functional language as opposed to non-functional.

B

Now, so functional programming is, I mean it's not a new thing,. It's been around for a long time, but there's a very long time. One could argue. Actually, some of the first languages were functional languages..

B

We just forgot. apparently. the java revolution and then yeah.

B

But there's plenty that are out there,, like you know: scala, clojure,, haskell, things like that.

B

And.Net has a functional language as well, f#.

B

And f# it's because it runs on.net. It also has support for objects and object, oriented programming and things like that, but it does have functional programming constructs, such that we kind of think of it as like. We say functional language, but also kind of a functional first language, meaning that when you write code, you want to do so in a functional manner,, but you can drop into objects kind of when it's convenient for you or if you want to interoperate with something or provide a clean api for c# callers, because c# is like it has.

B

Some functional programming constructs but not really a whole lot., and it's really at its heart. An object, oriented programming, language. so,, that's kind of where it differs, because c# is the one that most people know about for.net.

B

and that's oo at its heart, with some some functional, sprinkled, in.

B

and then,. F# is functional at its heart with some oo, not quite sprinkled in because it has a rather extensive object system,, but for the purposes of your code, you're likely going to.

B

Have a little sprinkle of object, oriented programming from time to time., make sense. now,. Is this true.

A

That scala is to java, as f# is to c#.

A

That's a pretty good way to think of it. Although,.

B

The family of languages that f# derives from,.

B

Is very different from what scala derives, from.

A

So, scala is kind of broken.

B

Into two categories of developers, I think,, I think, there's one that just kind of use it as a slightly better java or maybe a lot better kind of depending on their code base,, and they don't really go all that functional with it,.

B

They just kind of like the nicer syntax, and then there's people who go full fledged category theory.

B

Baked into their types super functional programming, all that sort of stuff.

B

java is capable of all that sort of stuff. But it's.

B

Derived from a different family of languages, now, as f# is right? the f# code, kind of as we have on our little website, here,.

B

It has kind of like these lights everywhere., you know. There's this thing. Pattern matching., like the syntax, looks a lot different in the way that you write. Your code is very different from the way that you would do scala., but for the purposes of a functional language running on a run-time,.

B

You could definitely think of it that way. yeah. now,, sometimes I think that,.

A

You have to be a type of specific type of person,.

B

To be successful, with functional languages.

A

So it's like oh yeah,, people who are a little bit more like academically oriented or those people that go into f#,, as opposed to just like regular programmers.

A

Those are the ones you c#rp, is that stereotype, reasonable.

A

At all, or as such as dead, false?.

B

Well,, it depends on how you look at it..

B

There are people in the functional programming and f# community who are just brilliant, people.

B

Like some people who are literally mathematicians and so on., I mean, you have those in the c# community as well. It's just you know, maybe you don't really hear about them as much.

B

B

A very utilitarian language, or to some people in the f# community, they say,.

B

"I'm kind of lazy and stupid and that's why I like f#, because I can be lazy and stupid and the compiler will yell at me when I do it." right. it 's, really reproachability and now.

A

That I think about it, that is really what I'm getting at.

B

Yeah, absolutely.

A

So, is it as approachable, would you say?.

B

I would argue that it totally is., I don't think it was in the past,, because there were, depending on the tool set, that you got,, you may have had to install additional things and they've been a bit more difficult to figure out where you can get started..

B

But so now we have this website on the.net, home page,.

B

Oh sorry,, a page on the.net website, reverse the two.

B

There's just a big fat button that says get started on f#. yeah.. What this does is this just takes you to a page where you just download the.net stk, and it just shows you hey how you can run something from the command line..

B

The key thing to note here is we don't even.

B

Really do anything special here with f#, because f# is a part of .net core..

B

So if you have.net core in your machine, you already have f# in your machine..

B

I think that's kind of a chasm that had to be crossed because before you had to say, "okay,, I got this thing that it can run on, but now I need to go get it so I can run on." well. How do I go do that?

B

you got to search online and then that additional step you just lose so many people who may have been just you know casually interested.

A

Now that is just part of it. I.

B

Think it's far more approachable, and of course we have tooling in visual studio..

B

I have seen this before.

A

Yes. so, how about,, I think, we've spent like five minutes on this topic., let's find out what's actually new here.

B

Yeah, absolutely. so,, you know...

A

This is visual studio, 2017 15.7.

A

Yes,, this is pretty five,.

B

It will be out of preview, pretty soon.

B

so,, I imagine by the time people are watching this. This will be the real full version.

B

so,. This it's... one thing to note,.

B

Is that I installed because I've done a core and all that stuff on their machine.? If I fight with the fire only project thing here and then get it.

B

you'll notice, that f# is already installed there..

B

I have some tabs here: for.net core,.net standard and web.

B

Then, on top of that, I also have this console application and library..

B

We are still trying to figure out how to name that appropriately kind of like classic f#. If you will, because we still have kind of the older stuff in there., it's just, now it's also there with the.net core stuff and so, like you know, there's some unit test projects, there,, there's this asp net core web app thing, which I think is pretty radical..

B

This is the exact same dialogue that you get with c#, just a little less templates, because we don't have the razor stuff in there because razor is dependent upon c#., but there's enabled doctors support..

B

I can go there and create a brand new project, the same way that you would do it in c# if it's installed by default- and I have my doctor compost stuff in there..

B

I even get the doctor error because I'm not running it on my machine right, now. note,. If you're going to.

B

Install doctor support- and you don't want to be freaked out by this thing,- make sure you have doctor actually running locally., yeah.

B

yeah,, but what's great, I can go to this publish tab and if you're inclined to publish via the ui, you could do that..

B

You could go to azure container registry, like I'm already doing some kind of advanced azure stuff right here. Just in a couple of clicks, all with f#,, I didn't have to install any additional stuff..

B

I see. so, what you're showing us now.

A

This is new? yeah,. This is all new.

B

You now going to be able to get this, in previous versions of visual studio., okay., so like,. If I wanted to publish this web application forward to a container registry, because I wanted that to be the base image for my organization to work on, well, I could do that and an unconnected with all the visual studio stuff that you would from a c# type application.

A

Or you just wanted to deploy that application to container service.

B

Yeah., that's the slightly more likely case. exactly. so,. The reason why that works is because we're on the same, what's called a product system., we're in the same project system as c#, and so you notice that there's this thing called microsoft.net.sdk.web specified in the project: file.

B

well,, basically, all the tooling in visual studio. All it does is looks for, if you are supported in this project model or type. If you will,- and you have this attribute we're just going to light up all this tooling for you., yeah. and so,. That world was sort of built for multiple languages and f# is fully supported. All of that.

B

A

Yeah. now,, so do you guys have globing turned off?.

B

Yes, we do.. The reason why we do is because in f#.

B

The compilation order the files matters.

A

B

That's because it uses type inference for everything.

B

Right. so, globing for the folks.

A

At home, is this basically idea of star dot star to pick up all the files? So you don't have to type them., so c# uses that because it's magic.

B

Yeah, and except for just one edge case in c#, where, if you have to,.

B

If you have a static constructor and you have.

B

Two partial classes, then the compilation order matters., that's actually the only edge case where it doesn't in every other area,.

B

Well, because then the compiler doesn't know what to initialize first,, but in f#, because it uses effectively global type inference to figure out what all the types are. like for example,. I can hover over this get in a table to.

B

Identify that it's taking an engine it produces a string.

B

Well,, I didn't specify the fact that it produces a string.. The compiler actually figured that out, based on how I define the function.

B

but,. If you want this to be actually efficient, well,.

B

Then you need to have your order files, because if you specify a different type- and you want to have something depend on that- type, well,, if the compiler has not already seen it,, then that algorithm will have to go and look for it and that could just explode and compile times.

B

and so,. That's why the ordering mechanism is there., makes sense.

A

Because of that, we have tools to order your files.

B

So,, if I wanted to actually cause this project to not compile,, I could go ahead and move this up, and then that would change the compilation, order.

B

and so,. If I go here in the fs prod you'll notice, that program.fs is now specified above startup.fs.

B

Understood. now, if I built this, this wouldn't work,, but I can just go ahead and move down again and there's key bindings for that so,.

B

You don't have to click the whole time.

B

you're aware of keyboard. yeah., but so there's plenty of other new stuff, coming along. so,, I'm going to do something a bit more interesting., so I'll just have a .net core console app.

B

So it was going to be more interesting, but console app is the most boring one of them. All.

A

Technically compilers are console apps,.

B

So that's kind of cool.

A

But I'm just going to go and manage.

B

New get packages here because there's this really, really cool feature of f# called type providers.

B

And type providers have been recently supported for .net core., the tooling for that, and getting all the stuff in the compiler and getting that into visual studio is going to be there with 15.7.

B

Some people are already playing around with it like on linux, machines, and so on,, but I want to show the experience in visual studio because it's really good.

B

so,, I'm just going to go ahead and install this package, and while we wait for it to download, type providers. Are things.

B

That the compiler can basically read.

B

and so, what happens is, this thing ingests the data source, and it builds out an object, model. and then,. The compiler is able to read that object. Model, and then, distribute it somewhere. well, that somewhere is intellisense.

B

and so,. You can effectively get intellisense for data,, which is really, really great. If you want to do some sort of basic exploratory, stuff.

B

so, I'll, just go and head to open fsharp.data,.

B

And so,: let's explore data source.

B

I was playing around with this, and I'm kind of interested in city statistics.

B

Oh, I love city statistics.,.

A

Yeah., do you know that toronto was the fifth largest city in north america?.

B

Oh yeah, and you're not totally not saying that, because you're canadian.

A

Yeah, totally not.

B

No. I bet toronto is really cool.. I want to visit it.

B

But so, what I'm just going to do here, is, paste any url.

B

So,, this is just the megacity article in wikipedia,.

B

And I'm creating a string literal with this literal, attribute. and so,. This is slightly different than if I removed it, and the reason why I'm going to do this is because I'm going to create a new type, and we'll just call this megacities,.

B

And we'll use this thing called the htmlprovider.

B

So,, what this will do? Is, you just pass in the url to its type argument: here.

B

okay., so,, I've saved that,.

B

And if you hover,, this is a type representation of an html file., so, basically,, you pass it in a string resource representing html, and then,. You can get an object model for it.

B

basically,, a [inaudible]., yeah. so, I'll go ahead and create a quick function..

B

Let's call it explorer, or something like that.

A

So,, what would have happened if you hadn't put the at symbol, there?

A

oh, in that case,.

B

I think it would actually be fine.. I just do that just by habit, because strings are always screwed up.

B

Okay. this one doesn't look too bad.

B

yeah. actually,. I think that would work just fine.

B

okay., but yeah, usually,.

B

If you have something like on a file on your machine or something,,.

A

You're going to have to do that. all of those slashes go the other way.

B

A

So,, that's about the whole escaping. yeah. nonsense.

B

Yeah., I usually just like to ignore having to deal with that and just go at, just by default.

B

So, then, we'll go ahead and go to let data equal to megacities.getsample.

B

Okay. so,: this is not like a production code, sort of thing that I'm doing right now., you may have noticed in the intellisense,.

B

There is an a async.getsample.

B

so,, that's for when you're loading, a resource asynchronously actually in your program., but because I'm just going to be doing some like data analysis stuff,, I don't care if it's asynchronous.

B

and so,. This data is now this htmlprovider of something.

B

Just out of curiosity,, can you just get.

A

Multiple samples on their additives such that it gets smarter about the data?

A

or is each time you call getsample, it's exclusive and replaces what it knew. Before?.

B

It replaces what it knew: before.

A

Okay. so, basically,, if, say,.

B

This content changed over time, or, say, I passed in a different url,. Then the data that I get is going to be different.

B

so, basically,. What this getsample call does is actually at design time.

B

so,. This literally happened on my machine..

B

It went in it, it fetched that html, document, and then,.

B

It downloaded it,, parsed it, uses just a standard, html provider, and built out an object model that it passed to the compiler. and the reason why I know that is because I just typed data dot, and all of a sudden,. I have this stuff called lists,, tables, and html.

B

so,. Let's go to tables, because if you remember, there was a little table of stuff there. so,, I'm just going to go ahead. instead of naming it. This discard underscore thing,, we'll just call it citytables, right?.

B

So,, let's do citytables.largest cities.

A

Oh, please. so, notice in intellisense,.

B

I get this thing called largest cities.

B

that was generated by the compiler, right?.

B

This is total, compile time stuff.

B

This name actually gets erased at runtime,, which is kind of cool.

B

At runtime or compile time?

B

at compile, time.

A

Yes,, because that would be super weird otherwise.

B

Yeah. and then, we'll go on the rows. so,. The rows are the actual cities there. notice. There was also a "headers" field.

B

So,, if I wanted a name out with all of the headers were,, I could go ahead and do that. understood., and if I were to print this out,, then I could print out the actual names..

B

But we actually have an interactive process called f# interactive that I would be using right now., but it's really difficult, work, and so,.

B

It's not quite ready to take this stuff and work every time., but once we have that,, then I won't have to actually just say that you could print it. Out.

B

I get it., it would be a repo . exactly. and that repo really comes in handy there.

B

Okay,, so rows is now an array of row.

B

So,, if you look at,, this is what the compiler inferred there. so,, we'll go array dot,, let's go groupby.

B

We'll go fun, row,.

B

And we'll go at row dot. lets see,. Do we want to group by country?.

A

Oh, I see. sure.

B

Yeah., let's do that. see,. These are questions that.

A

Or, no.: let's do it by continent, because.

B

I'll be able to test my theory.

A

Okay. yeah. but so,. This is pretty cool.

B

You can just be in your editor and start asking these questions like,. What do we want to group by?? We didn't have to go and read the table or data source, like in html., it's enough., but if this was a csv,, then that might not be so nice.

B

oh,, totally., right? and so,. There is a csv provider, for example.

B

so, now,. This is actually going to be a different kind of data that we have here.

B

So, we'll go fun, and then,.

B

This will be a continent,. I believe.

B

Will be a continent, and then,?

B

It's the rows that mapped that particular continent.

A

Yes. so,, if we hover over that continent as a string,.

B

And rows is an array of rows there.

B

Which makes sense.

A

B

So,, we could maybe do something like create a tuple here., so, basically,. What I did here is, this is a tuple type..

B

If you're familiar with c# tuples,.

A

The f# has had them for a while.

B

We'll just have that, and then, instead of just rows,, we'll do a rows piped into array.filter or something.

B

Actually,, we don't need this sort or anything. that could get tricky, because the data may not actually have numeric stuff that we could have there.

B

Or do we want to do that? that can be kind of tricky.

B

Actually,, I'm thinking it might just be simpler to just go ahead and take this because I'm thinking about how to transform this data right, here,.

B

And I can never think, and type, and talk at the same time. yeah. so, instead, we're just going to go ahead and take the top five, or something.

B

we'll go array.map, or go fun, row.

B

We'll go row.continents and row.population,.

B

And we'll pipe that into array.iter, and then we'll take that,.

B

That's a continent and that's a population, and then we'll go ahead and print that out.

A

B

So,, we'll go.

A

This looks pretty straightforward.. Yeah. is that,.

B

Let's see what type that is there., that's a string., okay. cool.

A

So, where good.

B

Population is also, oh,; it inferred it to be a string rather than an int.. I bet the html is formatted in a funky way.

A

Which meant that that sorting would have.

A

yeah, that sorting thing would have been onerous.

B

We had to do the with analog of [inaudible] parse.

B

It's got this little annotation on here., so we'd have to trim that out,.

B

That's just data cleaning,! That's like your typical data science, stuff. well, yeah,. Definitely something.

A

We don't need for this particular.. We don't want to bore people with that.

B

Okay, cool. all right.

B

so,, because I'm lazy.

B

And I like it when my code compiles, because I don't want to have to think it's going to compile for me,.

B

So let's go ahead and run that.

B

A

There we go. continent, asia, population, okay.,.

B

That was all the top five.. Let's actually take another one, here, we'll go row.megacity.

B

I bet that one's what it's called,, I bet- that's the actual city, there. so, notice that I added this thing right, here.

B

all of a sudden, now,, the compilers yelling at me, because I produced a tuple with three elements and I'm trying to capture a tuple of two elements, but it's saying, "hey,. These are three things: here." incompatible. so,, we'll call that city there and we'll go city,.

B

Do a percent s because I bet you it's a string as well.

A

I see. yes,. This makes sense, now.

B

Okay. so, we'll run that again, and, as I was saying, with f# interactive,, this will be even faster.: okay. so,, tokyo,, shanghai,, jakarta,, delhi, and seoul..

B

Those are some big cities. are the ones, yeah. unfortunately, toronto's, not in there.

A

Yes, well,, I never said worldwide.

B

I wish that weren't, the case,, but also I didn't really talk about some of the cool stuff. That's going on here., first of all,. We have this double tick, stuffed where you could have actual sentences and real words in there and intellisense is able to pick that up..

B

We have a semantic highlighting and.

B

Stuff like that, that you get with c#,, you can click in the hovers themselves to go to definition,, and this will work across projects and stuff. so,. If you see some useful information in here,.

B

You could actually just navigate to it there rather than.

B

Have to then back out and then invoke go to definition there.

B

this is fairly modern, tooling, and on top of that, with the 15 7 release,, we've done a whole lot of work in performance, especially in memory reductions, because we've been doing a lot of investigative work and reaching out to customers who have very large solutions..

B

Basically, I'm saying, "hey, memory usage is way too high,.

B

We basically have to restart visual studio sometimes,", and then we said, "that's a real problem," and we've encountered that on our own code base as well. so,. We addressed that with 15.7.

B

People are going to be happier.

A

Yeah. memory usage is.

B

Significantly reduced in this next release.

B

We were able to identify some places that were just insane in terms of what they were doing and with just a little bit of profiling and hard work,.

B

It got all better., it's still not perfect,.

B

This is an ongoing thing. As now we have clearly there's a lot of features in the ide, things like type providers and .net core are all working.

B

Now,, it's all about performance, reliability,,.

B

Responsiveness, that sort of stuff., because we say, okay,, we got all the features,. You can use .net core, basically anywhere.. I didn't even show it on the mac, but you can just do that within cli. If you like., even though this is a mac.

B

A

That was too hard.

B

But that's kind of where we're going now.

B

Basically, we have this vision of tooling ubiquity.

B

And quality for f# for a functional, language.

B

so,. If you go with f#,, you get just ubiquity of tooling of an extremely high quality anywhere you want.

B

so,. The ubiquity thing is effectively solved. Now.

B

We now want to go with quality and all the different cool features, like type providers being available, everywhere. awesome.. I think we learned a lot today.

A

I'm clearly going to be a f# programmer after this.

A

No,, that was awesome.

A

Anything else you want to leave us with in terms of like.

A

A call to action or some advice or whatever?.

B

Yeah., I would say step one, if you already have visual studio,, just open up your installer.

B

Of course, it might take a little while.. Hopefully it doesn't need to update.

B

yes,, I hope not., but if you actually already have .net core through visual studio on your machine,, it's all you've got to do is file a new project..

B

You don't have to do anything. Else. right.! You already have f# there,. You can start going.

B

if you don't have visual studio with .net core ,.

B

You could do that on your windows, machine and after it's been getting some things: ready,, there's a variety of workloads..

B

There are choices. yeah, like sapnet and web development workload and the azure development workload.. These things have f# because they depend on .net core and then same thing with the .net core cross platform, development, work.

A

So,, giving us a .net core was a good plan for you.

A

yes.. It wasn't a bad one, I'll put it that way.

B

Also,, if you don't use visual studio,, if you're on a mac or if you're on linux or something like that,, just go to aka.ms/fsharphome,.

B

That's a-k-a.m-s/fsharphome.

B

And that'll take you to this site. it's under /net/learn/languages/fsharp..

B

If you don't want to remember that,, we just have that little vanity url. just click the button that says get started with f#..

B

It's got everything on there, shows you how to get started. because I'm on a mac,, it shows me instructions there,.

B

It tells me to use visual studio for mac,, which also has f# support..

B

If I'm on linux, it'll tell me to use visual studio code and the i9 f# extension,, which is the official f# extension, that's maintained by our amazing open-source community..

B

If you're on windows, it'll tell you to use that.

B

it'll, take you to a link to some docs,.

B

We have a tour of f#.. If you want to learn about some of the major features and what everything looks like,, it's there.. We have some get started guides in the .net docs.

B

I think you can actually just search for f# in google, and this is one of the first things that comes up. must be a great doc.

B

Yeah. there's the full language reference as well.

B

so,. If you're curious about specific features,, it's all documented there.. If you want to learn how to use it on azure,, we have that..

B

This is also an active area,. We're going to be adding a style guide, pretty soon to show you not just formatting styles, but also just general programming idioms in f#.

B

so, that as you're learning the language,, you can feel like you're doing it the right, way. because,. I do that a lot. Whenever I learn a new language., I get hindered and I'm, like, "oh no,", but I don't want to continue because I might be doing it wrong..

B

We want to solve that as well,.

B

So that's another in-progress thing: that's [inaudible] been there, done. That. okay,, thanks.,.

A

This was great. well, thanks for coming by.

A

we'll have to do this again,, maybe when we ship, 159 or 1510, or something like that,.

A

See where we've got to.

A

okay. thanks for listening to another episode of the.

A

On.Net show and learning a little more about f#. thanks., bye, bye.