F# Basics An Introduction to Functional Programming for .NET Developers

http://msdn.microsoft.com/en-us/magazine/ee336127.aspx

by gspyrou • 16 years ago

51 19 16 years ago

msdn.microsoft.com

giu• 16 years ago

If you want to dig deeper into F#, have a look at The F# Survival Guide, which is a free online guide that was posted here on HN some time ago: http://www.ctocorner.com/fsharp/book/default.aspx

Edit: Here's the link to the original post: http://news.ycombinator.com/item?id=1109754

Stasyan• 16 years ago

Or if you don't mind spending money, then buy Expert F#: http://apress.com/book/view/1590598504

gtani• 16 years ago

The intro books by Smith ("programming F#", Oreilly) and Pickering (Beginning F#", Apress) are excellent, too. They were published last October and December, and cover what will be in VS 2010

seanos• 16 years ago

There's also the Wikibook: http://en.wikibooks.org/wiki/F_Sharp_Programming

jpatte• 16 years ago

Could anyone give some examples of instructions which are easily implemented in F# and would be really hard to implement in C#? From what I see here, F# seems nice and clean, but does not add a lot of value compared to LINQ-powered C#.

DrJokepu3• 16 years ago

A few things:

* Inbuilt support for sequence head and tail - very important for recursive functions.

* Due to the heavily object-oriented nature of C#, type inference is really limited. This makes writing anything non-trivial in functional style rather tedious as your type declarations will become several lines long really quickly. For example, try writing a Y Combinator in C# and F# to see the difference.

* Parallel processing is a lot easier in F#.

* Matching in F# is a lot more powerful than switch-case in C#, which makes functional programming easier.

My point is: functional programming support in C# is good enough for simple things but serious functional programming is a lot easier in F#. On the other hand, OO is a bit cumbersome in F#. I wouldn't use F# for typical web or enterprise create-update-delete database stuff but it is really great for things where functional programming is usually strong at, especially if you need it to work together with C# code.

MichaelGG3• 16 years ago

What is your reason for not using F# in a "typical web" app? Just developer experience and tools, or something with the actual language?

mquander• 16 years ago

Pattern matching and discriminated unions make code for structuring and destructuring complicated data really clean and pleasant to work with. Compiler implementation is the obvious application, but in a "businessy" setting, I sure wish that some of the EDI code I work with periodically was in F# instead of C#.

MichaelGG3• 16 years ago

There are plenty of things. From real-world experience, F# code ends up taking a bit less than half the amount of lines as C# does. More interestingly, the number of type annotations can be as little as 1/20th as in C#.

The benefit comes from that many "small" things you do in C# become much nicer in F#:

C#:

  int target;
  int someValue;
  if (dict.TryGetValue("key", out someValue)) {
      target = someValue * 100;
  } else {
      target = 42; // default
  }

F#:

  let target = match dict.TryGetValue "key" with
               | true, x -> x * 100
               | _	   -> 42 // default

Not only is the code more concise in F#, we get another benefit too. The temporary value x, needed because of the use of out params in C#, no longer exists in the F# version. In C#, this temp val escapes its needed scope - it should only be needed in the branch where it's used, but instead it's now a normal local.

A more large scale win is any async code. In F#, you can use the async workflow (monad), and with 1 character (!), you make the compiler emit code that'd take at least 10 extra lines in C#. Inside an async workflow, a let! (example: let! foo = bar.AsyncGetResponse()) is like calling bar.BeginGetResponse, bar.EndGetResponse, while preserving the current exception handlers and all locals. It makes heavily async code trivial to write, where in C#, it's near impossible.

runT1ME• 16 years ago

Thanks for this! Looks like a great language. Its a shame it targets the CLR and Mono is so crippled.

If it was on the JVM, looks like a serious competitor to Scala with some distinct advantages (! operator for sure) along with a little simpler syntax.

icco• 16 years ago

I've been coding in F# for the last few weeks at school, and I gotta say, F# takes everything good about SML/NJ, and rips it out. I mean it even makes the error messages more cryptic. The CLR is cool, but not worth destroying a language for it.

bmason2• 16 years ago

This seems like a bastardization of FP. I've been studying Clojure for the last few months and I'm amazed at the elegance of Lisp syntax. Maybe the perens have corrupted my brain, but F# just looks really ugly to me. It looks like Microsoft is trying to spoon feed it to C# developers, which is ok I suppose, but I don't think that people are really going to grasp the underlying concepts of FP without letting go of a lot of what they've learned in the imperative world. A familiar syntax can actually be an impediment in this effort, as it creates the impression that two expressions are equivalent when they really aren't.

F# Basics An Introduction to Functional Programming for .NET Developers

Related Stories