Cross platform native development in f#
0 likes277 views
This document provides an overview of cross-platform native development using F# and Xamarin. It introduces F# syntax including basic values like integers, floats and strings, lists, functions, pattern matching, data types like tuples, records, unions, classes, and interoperability. It also discusses cross-platform development with Xamarin, the MVVM pattern, and accessing device-specific services while sharing code across platforms.
![Basic Values
// ======== "Variables" (but not really) ==========
// The "let" keyword defines an (immutable) value
let myInt = 5
let myFloat = 3.14
let myString = "hello" //note that no types needed
// ======== Lists ============
let twoToFive = [2;3;4;5] // Square brackets create a list with
// semicolon delimiters.
let oneToFive = 1 :: twoToFive // :: creates list with new 1st element
// The result is [1;2;3;4;5]
let zeroToFive = [0;1] @ twoToFive // @ concats two lists](https://image.slidesharecdn.com/cross-platformnativedevelopmentinf-170727172829/85/Cross-platform-native-development-in-f-7-320.jpg)
Cross platform native development in f#
- 1. Cross-platform Native Development in F# David Y. Kay
- 2. ?
- 6. F# Syntax Overview (Several examples are from: F# For Fun and Profit)
- 7. Basic Values // ======== "Variables" (but not really) ========== // The "let" keyword defines an (immutable) value let myInt = 5 let myFloat = 3.14 let myString = "hello" //note that no types needed // ======== Lists ============ let twoToFive = [2;3;4;5] // Square brackets create a list with // semicolon delimiters. let oneToFive = 1 :: twoToFive // :: creates list with new 1st element // The result is [1;2;3;4;5] let zeroToFive = [0;1] @ twoToFive // @ concats two lists
- 8. Functions let square x = x * x // Note that no parens are used. square 3 // Now run the function. Again, no parens. let add x y = x + y // don't use add (x,y)! It means something // completely different. add 2 3 // Now run the function. // to define a multiline function, just use indents. No semicolons needed. let evens list = let isEven x = x%2 = 0 // Define "isEven" as an inner ("nested") function List.filter isEven list // FP’s classic filter a la “map/filter/reduce” evens oneToFive // Now run the function
- 9. Pattern Matching let simplePatternMatch = let x = "a" match x with | "a" -> printfn "x is a" | "b" -> printfn "x is b" | _ -> printfn "x is something else" // underscore matches anything let validValue = Some(99) let invalidValue = None let optionPatternMatch input = match input with | Some i -> printfn "input is an int=%d" i | None -> printfn "input is missing"
- 10. Data Types - I // Tuple types are pairs, triples, etc. Tuples use commas. let twoTuple = 1,2 let threeTuple = "a",2,true // Record types have named fields. Semicolons are separators. type Person = {First:string; Last:string} let person1 = {First="john"; Last="Doe"}
- 11. Data Types - II // Union types have choices. Vertical bars are separators. type Temp = | DegreesC of float | DegreesF of float let temp = DegreesF 98.6 // Types can be combined recursively in complex ways. // E.g. here is a union type that contains a list of the same type: type Employee = | Worker of Person | Manager of Employee list let jdoe = {First="John";Last="Doe"} let worker = Worker jdoe
- 12. Classes type LoginWindowViewModel(overseer: Overseer.Overseer) = inherit ViewModelBase() let mutable username = "" let mutable password = "" member this.Username with get () = username and set (value) = username <- value member this.Password with get () = password and set (value) = password <- value member this.LoginCommand = ViewModelHelpers.createCommand (fun o -> overseer.login (username, password)) (fun _ -> true)
- 13. Interop // Mostly very great: deviceContext.SoundPlayer.MessageReceived() // Some issues, including null-safety: let x: int option = Some 4
- 14. Cross-platform Development (Powered by Xamarin)
- 15. Xamarin
- 16. MVVM
- 21. Thanks!