Practical F#
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This document summarizes an introduction to the F# programming language presented at the Houston TechFest 2009. It covers core F# concepts like functional, object-oriented, and language-oriented programming paradigms. It also provides an overview of basic F# syntax, when to use F#, when not to use it, and resources for learning more about F#.
Practical F#
- 1. Practical F#Ryan RileyCatapult Systems, Inc.Houston TechFest 2009
- 2. AgendaCore ConceptsBasic SyntaxWhy Consider F#When to use F#When not to use F#Summary
- 5. Functional Programming ConceptsFirst-Class Functions (and Events)Strong Type InferenceImmutabilityMake side-effects explicit (the M-word)Functional Reactive ProgrammingEasy ConcurrencyActor-model Messaging (similar to Erlang)Lazy Evaluation
- 6. Basic Syntax
- 7. letSimilar to var in C#.
- 8. TuplesType-safe collection of valuesC# out parameters are returned as tuples
- 10. Abstract Classes
- 11. Interfaces
- 12. Inheritance
- 13. RecordsBut then, why bother?
- 15. Pattern Matching
- 18. Control Flow with Pipes
- 21. QuotationsThis is supposed to be a practical discussion!Quotations are similar to LINQ Expressions.
- 22. REPL
- 24. Why Consider F#?You can do everything you did in C# within F#Some things are simpler, some harderSimpler: many OO design patternsSimpler: Asynchronous tasksHarder: GUI programmingTerrific for specialized tasks (polyglot)Many great F# librariesTerse language = fewer lines of code = $ saved
- 25. When to use F#Asynchronous operationsConcurrent operationsMessaging (MailboxProcessor)Transformation operations (like SSIS)Computation-intensive operations (like SSAS)Creating Domain Specific Languages (DSLs)Aspect-Oriented Programming (AOP)Testing
- 26. FP vs. OOP
- 27. #1 Reason to use F# Your entire application is already just a series of LINQ statements!
- 30. Mathematical CalculationsProject Euler Problem 4:Project Euler Problem 3:Project Euler Problem 6
- 32. ParsersFSharp.PowerPack has a lexer and parserFparsecCashel
- 33. Automated Builds with Fake
- 34. Async Workflows
- 35. Async Workflows from C#
- 36. Functional AOP?
- 37. When not to use F# Just want to use the newest thingGUI programmingYou can do itCan’t use the designersCan still be a great toolWhen you are already proficient in C# and are focused almost entirely on OOP.Stick to what you know. You’ll be faster.
- 38. Summary“Write tomorrow’s legacy code today with C#”Chris Smith’s F# FactsTry F#Fall in love with F#Use F#The End
- 39. ResourcesF# is still CTPTry it in VS2010 Beta 1Or use the VS2008 CTP installerRead booksFoundations of F#(Pickering)Expert F# (Syme)Functional Programming for the Real World (Petricek and Skeet)F# for Scientists (Harrop)
- 41. The end …
- 42. MonadsMonads are about function composition.Take a monoid:f(x) -> xg(x) -> xf(g(x)) -> xf.g x -> xAdd a transformation:f(x) -> Mxg(x) -> Mxf(g(x)) -> Mxf.g x -> Mx
- 43. Creating Monadic BuildersThe parts of a monad:(in F#, this would be a workflow builder)x.Let (value, transform): sets a value, like LINQ’s Select().x.Bind (value, transform): splits the value from the transform and passes it into the next function, like LINQ’s SelectMany().x.Return (value): returns the result.x.Delay (transform): kicks off the workflow.
- 44. Computation workflow structureTypical structure of a workflow builder:type WorkflowBuilder () = member x.Bind (value, transform) = transform value member x.Return (value) = fun () -> value member x.Delay (transform) = fun () -> transform ()let workflow = new WorkflowBuilder()Execute like so:let myWorkflow = workflow { let x = 1 // x.Let let! y = 2 // x.Bind return x + y // x.Return }let result = myWorkflow () // x.Delay