Introduction to F# 3.0

Talbott Crowell, MVP

@talbott

#BOSCCBoston Code Camp

October 20, 2012

What is F#Statically typed, open

sourcefunctional programming

language that uses type inferencing

Unique features:Units of MeasureType Providers

Static versus Dynamic

F# is statically typed like:

C++, Objective-C, Java, Scala

Compared to dynamically typed languages:

Python, JavaScript, Erlang, MATLAB

Open SourceApache 2.0 licenseFree IDE on Windows from MicrosoftFree IDE on Mac (MonoDevelop)

http://blogs.msdn.com/b/fsharpteam/archive/2012/09/24/announcing-the-f-3-0-open-source-code-drop.aspx

Functional Programming (FP)

Examples of FP languagesErlang, Haskell, Clojure and Scala (JVM)

Functions are first class citizenslike variables in imperative languages

Higher-order functionsfunctions a parameters or return values

Type Inferencing

let x = 5let y = "hello"let z = new Form()let distance = 26.21875<mile>let f x = x + x

Immutable by default

let x = 5let mutable y = 7y <- 8

let z = new Form()z.Show()z.Text <- “Hello”

Array, List, and Seq

Arrays are mutable

Lists are not

Seq (sequences) only store one value at a time (lazy)

Array, List, and Seq

let set1 = [|1..10|]let set2 = [1..10]let set3 = seq { 1..10 }

set1.[0] <- 999 //mutable

Units of MeasureFloating point and signed integer values in F# can have associated units of measure, which are typically used to indicate length, volume, mass, and so on.

By using quantities with units, you enable the compiler to verify that arithmetic relationships have the correct units, which helps prevent programming errors.

Units of Measure

[<Measure>] type mile[<Measure>] type km

let distance1 = 4.0<mile>let distance2 = 3.0<km>//compile errorlet total = distance1 + distance2

Units of Measure

[<Measure>] type mile[<Measure>] type kmlet convert_mile2km (a : float<mile>) = a / 0.621371<mile/km>

let distance1 = 4.0<mile>let distance1a = convert_mile2km distance1let distance2 = 3.0<km>

let total = distance1a + distance2

Type ProvidersF# 3.0 introduces Type Providers

Data rich programming for the Big Data Era

Enables massive schemas with strict typing

Examples of Type Providers

SQL Data ConnectionOData Service Provider (Netflix)

FreebaseHadoop

RWMI

RegEx

Type Provider Demo

TryFsharp.org

FPish.net

Other Resourceshttp://stackoverflow.com/questions/tagged/f%23

http://fsharpsamples.codeplex.com/

http://fsharp.net

Questions?

Thank You

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