diff options
Diffstat (limited to 'fsharp.html.markdown')
| -rw-r--r-- | fsharp.html.markdown | 90 |
1 files changed, 43 insertions, 47 deletions
diff --git a/fsharp.html.markdown b/fsharp.html.markdown index 76318d7d..e345201d 100644 --- a/fsharp.html.markdown +++ b/fsharp.html.markdown @@ -31,14 +31,14 @@ If you want to try out the code below, you can go to [tryfsharp.org](http://www. // The "let" keyword defines an (immutable) value let myInt = 5 let myFloat = 3.14 -let myString = "hello" //note that no types needed +let myString = "hello" // note that no types needed // ------ Lists ------ -let twoToFive = [2;3;4;5] // Square brackets create a list with +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 +// The result is [1; 2; 3; 4; 5] +let zeroToFive = [0; 1] @ twoToFive // @ concats two lists // IMPORTANT: commas are never used as delimiters, only semicolons! @@ -53,7 +53,7 @@ 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 a sub function + let isEven x = x % 2 = 0 // Define "isEven" as a sub function List.filter isEven list // List.filter is a library function // with two parameters: a boolean function // and a list to work on @@ -75,7 +75,7 @@ let sumOfSquaresTo100piped = // you can define lambdas (anonymous functions) using the "fun" keyword let sumOfSquaresTo100withFun = - [1..100] |> List.map (fun x -> x*x) |> List.sum + [1..100] |> List.map (fun x -> x * x) |> List.sum // In F# there is no "return" keyword. A function always // returns the value of the last expression used. @@ -109,7 +109,7 @@ optionPatternMatch invalidValue // The printf/printfn functions are similar to the // Console.Write/WriteLine functions in C#. printfn "Printing an int %i, a float %f, a bool %b" 1 2.0 true -printfn "A string %s, and something generic %A" "hello" [1;2;3;4] +printfn "A string %s, and something generic %A" "hello" [1; 2; 3; 4] // There are also sprintf/sprintfn functions for formatting data // into a string, similar to String.Format in C#. @@ -131,19 +131,19 @@ module FunctionExamples = // basic usage of a function let a = add 1 2 - printfn "1+2 = %i" a + printfn "1 + 2 = %i" a // partial application to "bake in" parameters let add42 = add 42 let b = add42 1 - printfn "42+1 = %i" b + printfn "42 + 1 = %i" b // composition to combine functions let add1 = add 1 let add2 = add 2 let add3 = add1 >> add2 let c = add3 7 - printfn "3+7 = %i" c + printfn "3 + 7 = %i" c // higher order functions [1..10] |> List.map add3 |> printfn "new list is %A" @@ -151,7 +151,7 @@ module FunctionExamples = // lists of functions, and more let add6 = [add1; add2; add3] |> List.reduce (>>) let d = add6 7 - printfn "1+2+3+7 = %i" d + printfn "1 + 2 + 3 + 7 = %i" d // ================================================ // Lists and collection @@ -168,12 +168,12 @@ module FunctionExamples = module ListExamples = // lists use square brackets - let list1 = ["a";"b"] + let list1 = ["a"; "b"] let list2 = "c" :: list1 // :: is prepending let list3 = list1 @ list2 // @ is concat // list comprehensions (aka generators) - let squares = [for i in 1..10 do yield i*i] + let squares = [for i in 1..10 do yield i * i] // prime number generator let rec sieve = function @@ -190,8 +190,8 @@ module ListExamples = | [first; second] -> printfn "list is %A and %A" first second | _ -> printfn "the list has more than two elements" - listMatcher [1;2;3;4] - listMatcher [1;2] + listMatcher [1; 2; 3; 4] + listMatcher [1; 2] listMatcher [1] listMatcher [] @@ -219,7 +219,7 @@ module ListExamples = module ArrayExamples = // arrays use square brackets with bar - let array1 = [| "a";"b" |] + let array1 = [| "a"; "b" |] let first = array1.[0] // indexed access using dot // pattern matching for arrays is same as for lists @@ -230,13 +230,13 @@ module ArrayExamples = | [| first; second |] -> printfn "array is %A and %A" first second | _ -> printfn "the array has more than two elements" - arrayMatcher [| 1;2;3;4 |] + arrayMatcher [| 1; 2; 3; 4 |] // Standard library functions just as for List [| 1..10 |] - |> Array.map (fun i -> i+3) - |> Array.filter (fun i -> i%2 = 0) + |> Array.map (fun i -> i + 3) + |> Array.filter (fun i -> i % 2 = 0) |> Array.iter (printfn "value is %i. ") @@ -248,14 +248,14 @@ module SequenceExamples = // sequences can use yield and // can contain subsequences let strange = seq { - // "yield! adds one element + // "yield" adds one element yield 1; yield 2; // "yield!" adds a whole subsequence yield! [5..10] yield! seq { for i in 1..10 do - if i%2 = 0 then yield i }} + if i % 2 = 0 then yield i }} // test strange |> Seq.toList @@ -280,11 +280,11 @@ module DataTypeExamples = // Tuples are quick 'n easy anonymous types // -- Use a comma to create a tuple - let twoTuple = 1,2 - let threeTuple = "a",2,true + let twoTuple = 1, 2 + let threeTuple = "a", 2, true // Pattern match to unpack - let x,y = twoTuple //sets x=1 y=2 + let x, y = twoTuple // sets x = 1, y = 2 // ------------------------------------ // Record types have named fields @@ -297,7 +297,7 @@ module DataTypeExamples = let person1 = {First="John"; Last="Doe"} // Pattern match to unpack - let {First=first} = person1 //sets first="john" + let {First = first} = person1 // sets first="John" // ------------------------------------ // Union types (aka variants) have a set of choices @@ -331,14 +331,14 @@ module DataTypeExamples = | Worker of Person | Manager of Employee list - let jdoe = {First="John";Last="Doe"} + let jdoe = {First="John"; Last="Doe"} let worker = Worker jdoe // ------------------------------------ - // Modelling with types + // Modeling with types // ------------------------------------ - // Union types are great for modelling state without using flags + // Union types are great for modeling state without using flags type EmailAddress = | ValidEmailAddress of string | InvalidEmailAddress of string @@ -346,7 +346,7 @@ module DataTypeExamples = let trySendEmail email = match email with // use pattern matching | ValidEmailAddress address -> () // send - | InvalidEmailAddress address -> () // dont send + | InvalidEmailAddress address -> () // don't send // The combination of union types and record types together // provide a great foundation for domain driven design. @@ -383,8 +383,8 @@ module DataTypeExamples = type Rank = Two | Three | Four | Five | Six | Seven | Eight | Nine | Ten | Jack | Queen | King | Ace - let hand = [ Club,Ace; Heart,Three; Heart,Ace; - Spade,Jack; Diamond,Two; Diamond,Ace ] + let hand = [ Club, Ace; Heart, Three; Heart, Ace; + Spade, Jack; Diamond, Two; Diamond, Ace ] // sorting List.sort hand |> printfn "sorted hand is (low to high) %A" @@ -419,14 +419,14 @@ module ActivePatternExamples = | _ -> printfn "%c is something else" ch // print a list - ['a';'b';'1';' ';'-';'c'] |> List.iter printChar + ['a'; 'b'; '1'; ' '; '-'; 'c'] |> List.iter printChar // ----------------------------------- // FizzBuzz using active patterns // ----------------------------------- // You can create partial matching patterns as well - // Just use undercore in the defintion, and return Some if matched. + // Just use underscore in the definition, and return Some if matched. let (|MultOf3|_|) i = if i % 3 = 0 then Some MultOf3 else None let (|MultOf5|_|) i = if i % 5 = 0 then Some MultOf5 else None @@ -479,7 +479,7 @@ module AlgorithmExamples = List.concat [smallerElements; [firstElem]; largerElements] // test - sort [1;5;23;18;9;1;3] |> printfn "Sorted = %A" + sort [1; 5; 23; 18; 9; 1; 3] |> printfn "Sorted = %A" // ================================================ // Asynchronous Code @@ -526,7 +526,7 @@ module AsyncExample = |> Async.RunSynchronously // start them off // ================================================ -// .NET compatability +// .NET compatibility // ================================================ module NetCompatibilityExamples = @@ -536,7 +536,7 @@ module NetCompatibilityExamples = // ------- work with existing library functions ------- - let (i1success,i1) = System.Int32.TryParse("123"); + let (i1success, i1) = System.Int32.TryParse("123"); if i1success then printfn "parsed as %i" i1 else printfn "parse failed" // ------- Implement interfaces on the fly! ------- @@ -570,12 +570,12 @@ module NetCompatibilityExamples = // abstract base class with virtual methods [<AbstractClass>] type Shape() = - //readonly properties + // readonly properties abstract member Width : int with get abstract member Height : int with get - //non-virtual method + // non-virtual method member this.BoundingArea = this.Height * this.Width - //virtual method with base implementation + // virtual method with base implementation abstract member Print : unit -> unit default this.Print () = printfn "I'm a shape" @@ -586,19 +586,19 @@ module NetCompatibilityExamples = override this.Height = y override this.Print () = printfn "I'm a Rectangle" - //test - let r = Rectangle(2,3) + // test + let r = Rectangle(2, 3) printfn "The width is %i" r.Width printfn "The area is %i" r.BoundingArea r.Print() // ------- extension methods ------- - //Just as in C#, F# can extend existing classes with extension methods. + // Just as in C#, F# can extend existing classes with extension methods. type System.String with member this.StartsWithA = this.StartsWith "A" - //test + // test let s = "Alice" printfn "'%s' starts with an 'A' = %A" s s.StartsWithA @@ -627,7 +627,3 @@ module NetCompatibilityExamples = For more demonstrations of F#, go to the [Try F#](http://www.tryfsharp.org/Learn) site, or my [why use F#](http://fsharpforfunandprofit.com/why-use-fsharp/) series. Read more about F# at [fsharp.org](http://fsharp.org/). - - - - |