Why F# for the Enterprise

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I have gotten bit by the F# bug lately. After helping to release the F# portion of Exercism I've started to enjoy more and more of what F# has to offer. Of course, F# is a sort of "hybrid" language where you can do object oriented and procedural programming if you make it that way, but out of the box it's trying to get you to go more functional.

Several folks have posted as to why learn F# in the first place, but I figured I'd give some reasons why I think F# would be great for scenarios inside enterprise applications. While a few what others have mentioned as good reasons to learn F# in the first place, I believe these would also be the top reasons for enterprise development.

What's wrong with the current enterprise solutions?

Well, nothing, really. Of course, just because one solution works doesn't mean it's the most productive or easiest to maintain. For example, CSS precompilers like SASS and LESS do this with plain CSS stylesheets.

Why not use something that makes our lives, as developers, easier and helps to bring back the fun in developing again?

No More NullReferenceExceptions

While the above always tends to make me laugh, I'm quite sure each and every developer has fixed a production defect that involved this error. 

In F# there are is no thought of "null". You'll even get a compiler error if you try to use "null" in a pure F# program. For example, take a peek at the below code:

We're just defining some record types - Person and Employee - and let binding the Employee record with some values. Now, what happens if I set Person to null?

The compiler won't even let us try that...

Trying to assign null to a record type.

So this shows that, in pure F# code, the compiler won't allow us to set records as null which greatly reduces, perhaps even eliminates, NullReferenceExceptions.

What if we still need null?

There are some exceptions where F# will allow you to use null. Both of which involve using the .NET libraries.

  • As a parameter when calling one of the .NET libraries.
  • Handling if a call to a .NET library returns null.

Even using null in these scenarios can greatly reduce the NullReferenceException occurring in your application. To me, that's just one less thing I need to worry about.

But I still need it in my F# code

No worries! The language has you covered on that aspect as well. Allow me to introduce the option type. This is used if a value might not exist.

Let's take a small example of a bank account.

If the account isn't open yet or has already been closed, we don't expect a value. Otherwise, we do expect some value.

None vs null

How is this different than assigning to null? Remember that None is an option type. Because of that, the compiler will help us out if we may have missed anything. For example, in F# you can do pattern matching. Let's see how we can use pattern matching with the option type.

Good to go there. But, what if we happened to miss a match on None? We'll get this warning:

Pattern match warning.

Units of Measure

Units of Measure allow you to explicitly type a certain unit. F# does have predefined unit names and unit symbols in the Microsoft.FSharp.Data.UnitSystems.SI.UnitNames and Microsoft.FSharp.Data.UnitSystems.SI.UnitSymbols namespaces.

For example, say we wanted to use meters. Instead of assuming our application is using meters throughout all the calculation, which has a probability of being converted to another unit but still being represented as meter, we would just need to do the following:

Microsoft has included a few units of measure for us, as mentioned earlier, but we can definitely create our own. Say we had an application that dealt with different types of world currencies. We can easily define them as units of measure.

Now, what does this do for us exactly? Let's try to convert how many euros are in a dollar amount.

The first method we defined works just fine since we're using the units of measure. However, the second method generates a compile error since it can't infer what type "0.74" should be.

Since a unit of measure is typed, it will generate compile errors and reduce the amount of defects your application can cause due to a mismatch of units. This type of error does happen in real world applications...even to NASA engineers.

Type Providers

Type providers in F# is essentially a way to access all sorts of data. There are quite a few of them all ready for you to use now.

Just the SQL type providers alone are worth it for enterprise applications. Even better, you can even use them to access Entity Framework and LINQ to SQL.

Another important one that may be of great use to enterprise applications is the JSON type provider. 

Type providers provide an easy way to consume data within F# and, if you'd like, use C# to handle that data.

 

The above are just a few reasons of why I believe F# to be of great use to developing enterprise applications. Using the above, the risks of error would be greatly reduced and productivity would be increased. I know I'll be doing more F# in my applications from now on and I can only see it getting even better in the future as this language evolves.

Exercism F# Track Now Available

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Wait....F#?

Yep. After attending an interesting talk by James Dixon on data in F# I got a bit interested in the language. Of course, that's followed by reading articles, watching videos, and playing with it a bit on my own. The past month or so I've been messing around with it and plan on sticking to it for a while.

I can see F# going places in terms of functional programming and it's uses within .NET. Be prepared for more F# posts in the future, as well.

What is Exercism?

In short, Exercism is another site where people can learn a new programming language by doing different exercises. The difference with this one than the others, however, is that it's crowd-sourced. Meaning that, once you finish an exercise, you can send it off to be code reviewed by others.

It's definitely the best of both worlds where you practice the language and get peer reviews to help you learn that much quicker.

F# Track

And so, since I got interested  a bit more in F# and no one started messing with it in the Exercism F# repository, I figured I'd give it a shot. After a little while I was able to get it to meet the requirements to be launched!

Hopefully, I did decently in my own examples for the exercises (and if not, I'm not scared of some helpful tips), and that some people can get a bit of use out of it.

So feel free to give it a try and let me know or submit an issue if there are any problems!

JavaScript Garbage Collector Presentation

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Last time I mentioned that I would be giving a talk at a local event - the Carolina Code Camp. Well, today was that day and I'm happy to report that the presentation and the event as a whole went very well! I hope to refine the presentation even further to present again at future events.

For anyone interested the GitHub repository that holds the actual presentation with all links used is available to view.

For a working version of the presentation (latest version), it can be found here.

My First Speaking Engagement is Official

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I've often thought about being the one in front of the room during a code camp or some other speaking event. Though, like most of us, I've always been reluctant to put myself up there, scared that someone will call me out on not knowing what I was talking about or, worse yet, they all walk out on me.

However, with the fine coworkers at Wintellect and other friends, I decided to bite the bullet and sign up as a speaker for the Carolina Code Camp this year. After a couple of days of debating with myself on what to talk about, I decided that a talk on the JavaScript garbage collector would be interesting. I've always enjoyed learning about performance and this should be practical for others to learn as well.

So if you're near the Charlotte, NC area on Saturday, May 3, I encourage you to attend what has always been a great event since I've been going three years ago. Hope to see you there! If you end up going and even go to my session, try to refrain from throwing things.

The JavaScript Garbage Collector Demystified

Consuming the Jamendo API with AngularJS: Services

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It took a little while to get back to this little project. After watching some nice stuff from NgConf the other week, it helped get me excited again for AngularJs. Plus, I was stuck on a problem for quite a while that I'll explain in more detail below that really slowed me down. After a bit of a break I got back to it and was able to figure it out.

Services

Before we looked at how to use the $http get method from AngularJS, but all of that was within the Angular controller itself. To separate things out and to help us test easier I moved the $http calls into an Angular service.

To recap, let's take a look at our controller currently:

As mentioned earlier, we have our $http call right inside of our controller. While that definitely works, it's better to separate that out into it's own service. Let's refactor this down a bit...

Now this looks a bit cleaner. We're first passing in the albumsService as a dependency into the controller. Of course, if Angular can't find that the albumsService is defined, it'll throw an error.

Next, we have the function definition of our getAlbums method. In here we extract out the artist from the scope and then call the getAlbums method on our service. In our call to the service we give it a function as a callback if the $http get was a success that we'll see later when we look at our service. This basically just gets the results and puts them into the scope.

Now let's take a look at our service.

Pretty straight forward as it's basically the same as what we had in our controller earlier. We inject in the $http Angular object and we create our getAlbums method while prepending it with this. 

When we call our success promise from the get method, I just pass in the callback method that we defined in our controller earlier. This makes it a bit easier on our service since the callback method was updating our $scope object and we don't have to worry about that here in our service.

I mentioned earlier that I had a bit of an issue that kept me from finishing this up. I kept getting an $inject error on my service that indicated that it wasn't defined, but I couldn't figure out why that was. After some fiddling around with it, it turns out that I was trying to inject the $scope object into the service and Angular doesn't like that. That's also a reason to use the callback.

Conclusion

Moving the $http get call to an Angular service is mostly just a small refactoring, but it's a good one to do. We will see later when we start to do testing how much easier it is to have that separated out.

Of course, this was just an introduction to Angular services so there's tons more to learn about them. I'll recommend Dan Wahlin's AngularJS in 60ish Minutes to anyone. In fact, I've referenced it a few times to remind myself about services. There's also the WintellectNow video from Jeremy Likness on AngularJS Services that goes into much greater detail of services.

You can play with the demo and, as always, you can play around with the code itself.

First Wintellect Blog Post + A New Series On Design Patterns

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Just recently, I published my first blog post to the Wintellect (my awesome new employer) site. May not seem like much, but it's pretty exciting for me.

One of the things to keep yourself learning, I feel, is to tackle the stuff you feel you understand the least. For me, one of those things was the concept and implementation of different design patterns. I'm probably already too late in the game for this, but better than not learning it at all, right?

Head First Design Patterns - Part 1: Observer Pattern