Slides for my talk to the Bay Area Clojure User Group. Unlike most "entry level" F# talks, this presentation assumes some familiarity with functional programming concepts, although I think even folks unfamiliar with functional programming will find the content and demonstrations interesting. The talk includes a survey of the state of the F# community and community-driven (open source) projects.

1. F# for Functional Enthusiasts
Jack Fox
jackfoxy.com  craftyThoughts
@foxyjackfox
Bibliography
jackfoxy.com/Fsharp_functional_enthusiasts_bibliography
Sample Code
https://gist.github.com/jackfoxy/6679238
https://github.com/jackfoxy/CrockSolution
https://github.com/jackfoxy/TestSandbox
2012 annular eclipse observed by the author from Sugarloaf Peak, Lake Shasta

2. Type Providers
Microsoft.FSharp.Data.TypeProviders
DbmlFile
EdmxFile
ODataService
SqlDataConnection
SqlEntityConnection
WsdlService
Fsharpx
AppSettings
Excel
Graph
Machine
Management
Math
Regex
Xaml
Xrm
FSharp.Data
Apiary
Csv
Freebase
Json
WorldBank
Xml
F# 3.0 Sample Pack
DGML
Word
Csv
DataStore
Hadoop/Hive/Hdfs
HelloWorld
Management
MiniCvs
Xrm
Tsunami
RSS Reader
Start Menu
NuGetTypeProvider *
S3TypeProvider *
FacebookTypeProvider *
DocumentTypeProvider *
* (samples inside Tsunami)
in the wild on Github
FunScript
R
Matlab
IKVM (Java)
Python
PowerShell

3. strongly typed ≠ object oriented
Typed Clojure project on indiegogo.com

4. Parameterized Polymorphism
a.k.a. Generics
let inline unsigned bitSize (zero : 'a) (one : 'a) =
let one' = one + zero
let x' = one <<< (bitSize - 1)
x' ||| one'
bitSize:int -> zero: ^a -> one: ^a -> ^a
when ^a : (static member ( + ) : ^a * ^a -> ^a) and
^a : (static member ( <<< ) : ^a * int32 -> ^a) and
^a : (static member ( ||| ) : ^a * ^a -> ^a)

5. // Base Type Constraint
type Class1<'T when 'T :> System.Exception> …
// Interface Type Constraint
type Class2<'T when 'T :> System.IComparable> …
// Comparison constraint
type Class10<'T when 'T : comparison> …
// Member constraint with property
type Class6<'T when 'T : (member Property1 : int)> …
Constraints on Type Definitions

6. [<Measure>] type m // Distance, meters.
[<Measure>] type mile // Distance, miles.
[<Measure>] type s // Time, seconds.
[<Measure>] type h // Time, hours.
let distance1 = 100.0<m>
let distance2 = 250.0<mile>
let speedMetersPerSec = distance1 / 10.0<s> // float<m/s>
let speedMPH = distance2 / 5.0<h> // float<mile/h>
let x = distance1 + distance2 //will not compile
Units of Measure
Design Time Type Checking

7. So far…
Type Providers: strongly typed external data
Strong typing and type inference
Type constraints
Units of Measure
Next up…
Nuts and bolts programming

8. Vector
Eager Rose Tree

9. Vector
54321
Construct
Deconstruct
Initia
l
Las
t
[ ]
empt
y
;
;

10. type JsonValue =
| String of string
| Number of decimal
| Float of float
| Object of Map<string, JsonValue>
| Array of JsonValue[]
| Boolean of bool
| Null
JSON Parsing
Discriminated Union Type from
FSharp.Data

11. JSON Parsing
Demo Crock Solution
FSI (REPL) compiles to assembly and executes
F# scripts
Fseye
Triple quoting

12. Red Black Tree Balancing
Source: https://wiki.rice.edu/confluence/download/attachments/2761212/Okasaki-Red-Black.pdf
a b
c
d
b ca d
a
a
b c
d
b c
d
a
c
b
d

13. Talk about reducing complexity!
type 'a t = Node of color * 'a * 'a t * 'a t | Leaf
let balance = function
| Black, z, Node (Red, y, Node (Red, x, a, b), c), d
| Black, z, Node (Red, x, a, Node (Red, y, b, c)), d
| Black, x, a, Node (Red, z, Node (Red, y, b, c), d)
| Black, x, a, Node (Red, y, b, Node (Red, z, c, d)) ->
Node (Red, y, Node (Black, x, a, b), Node (Black, z, c, d))
| x -> Node x
Source: http://fsharpnews.blogspot.com/2010/07/f-vs-mathematica-red-black-
trees.html

14. Computational Expressions
One syntactic sugar to rule them all
( monad, monoid, applicative functor )
seq {for n in 1..10 do
yield n
yield n * 2}
seq {for n in 1..10 do
yield (n, n * 2)}
Sequence Generators

15. Computational Expressions
Recursive Generators
let rec listFiles dir = seq {
yield! Directory.GetFiles(dir)
for subdir in Directory.GetDirectories(dir) do
yield! listFiles subdir }
let musicFiles = listFiles "E:music" |> List.ofSeq

16. Computational Expressions
Query Expressions
let htmlPage =
query { for content in db.tbContentLib do
where (content.companyID.Value > 0 and content.isHtml)
join template in db.tbTemplate on
(content.templateID.Value = template.templateID)
select (content.styleID, template.title, template.body)
}

17. Computational Expressions
Query Expressions (Freebase)
let topBooksWithNameContaining (s:string) =
query { for book in
data.``Arts and Entertainment``.Books.Books
do
where (book.Name.ApproximatelyMatches s)
take 10
select book.Name }

18. Async
let someBinding =
async {
let! x = … // asynchronous binding
let y = … // synchronous binding
let! z = … // another asynchronous binding
do! … // asynchronous execution
return z // return something (or not)
}

19. Agents
a.k.a. Mailbox Processor
Message passing
Actor Model
Erlang-like processing

20. {m}brace
Cloud Computing (beta)
[<Cloud>]
let calculatePi (iterations : bigint) (digits : int) : ICloud<string> =
cloud {
let! workers = Cloud.GetWorkerCount()
let workers = bigint (2 * workers)
...
let runWorker iterations = cloud { return monteCarloPiWorker iterations }
let! results =
...
|> Cloud.Parallel
...
return getDigits a b
|> ...
}

21. Quotations
let ``Vector<Vector<'T>>, windowSeq``() =
test<@ [0; 1; 2; 3; 4; 5; 6; 7; 8; 9; 10;] =
([0; 1; 2; 3; 4; 5; 6; 7; 8; 9; ]
|> Vector.windowSeq 3
|> Vector.flatten
|> List.ofSeq) @>

22. Now we’ve seen…
ML-style pattern matching
Syntactic sugar over common FP abstractions
Async and friends
Quotations
Next: Community-Driven Development
Fsharp.org
Some “core” projects
Dev environments

23. Fsharp.org
F# Foundation
Owns resources relating to F# including:
the domain fsharp.org
the github.com/fsharp community organization
the fsharporg twitter account
Seeks to:
promote the adoption of F#
expand the relevance and importance of F# skills and knowledge
expand the range of technologies which can interoperate with F#
expand the range of platforms where F# can be used
facilitate the ongoing development of F#-related technology and resources

24. FAKE
 DSL implementation of build automation system
 Full use of F# language
 Access to any and all libraries
 Develop with powerful debuggers and IDEs

25. Literate Programming
FSharp.Formatting

26. Funscript
Javascript and Single Page Apps
JQuery and Javascript DOM APIs
TypeScript TypeProvider
Mini Web Server

27. Websharper
Fully composeable client-server web development.
#websharper on irc.freenode.net

28. GPU Process
Alea.cuBase
Complete commercial solution to develop highly optimized
CUDA accelerated GPU applications from F# quotations by
QuantAlea.
Advantages of functional composition and rapid prototyping
Don’t have a NVIDIA card?
Try Brahma.Fsharp F# quotations to OpenCL translation

29. Testing Options
FsUnit – native F# functional syntax across test tools
FsCheck – QuickCheck for F#
TickSpec – lightweight, but fully featured Gherkin BDD
Canopy – lightweight F# syntax for web-client Selenium testing
Unquote – step-by-step F# expression evaluations

30. Development Alternatives
Tsunami IDE (beta)
Visual Studio 2010, 2012, 2013 (free Express edition)
Xamarin Studio -- iOS, Android, Mac, Mono, .NET
(free edition limits project size)
Emacs
Vim
SublimeText

31. IKVM lets Java and .NET Get Along!
Java from .NET, .NET from Java
JVM bytecode  IL instruction  native JIT
(not a bunch of wrappers)
10+ years of development effort
Actively supported
Powers Mono
Extremely few edge incompatibilities

32. Questions?
F# Programming
http://en.wikibooks.org/wiki/F_Sharp_Programming
A Course of F# Study
http://jackfoxy.com/a-course-of-fsharp-study
A directory of useful pages
http://fsharpforfunandprofit.com/site-contents
Learning F#