// This sample will guide you through elements of the F# language. 这个示例将会指导你通过F#语言的元素
//
// *******************************************************************************************************
// 为了交互执行F#代码，可以选择部分代码并按下Alt+回车，To execute the code in F# Interactive, highlight a section of code and press Alt-Enter or right-click
// 或者点击右键选择“交互执行”。你可以在“视图”菜单打开F#交互窗口and select "Execute in Interactive". You can open the F# Interactive Window from the "View" menu.
// *******************************************************************************************************
//
// 更多关于F#的，请看：For more about F#, see:
// http://fsharp.org
//
// 若要使用 F # 的其他模板，请参阅在 Visual Studio 中的在线模板For additional templates to use with F#, see the 'Online Templates' in Visual Studio,
// 新建项目-->在线模板'New Project' --> 'Online Templates'
//
// 具体的F#专题，请看：For specific F# topics, see:
// http://go.microsoft.com/fwlink/?LinkID=234174 （F#开发门户） (F# Development Portal)
// http://go.microsoft.com/fwlink/?LinkID=124614 （代码库）(Code Gallery)
// http://go.microsoft.com/fwlink/?LinkId=235173 （数学/统计编程）(Math/Stats Programming)
// http://go.microsoft.com/fwlink/?LinkId=235176 （图表）(Charting)
// 内容Contents:
// - 整型和基本函数Integers and basic functions
// - 布尔值Booleans
// - 字符串Strings
// - 元组Tuples
// - 列表和列表处理Lists and list processing
// - 类Classes
// - 泛型类Generic classes
// - 实现接口Implementing interfaces
// - 数组Arrays
// - 数列Sequences
// - 递归函数Recursive functions
// - 记录类型Record types
// - 联合类型Union types
// - 选项类型Option types
// - 模式匹配Pattern matching
// - 计量单位Units of measure
// - 并行数组编程Parallel array programming
// - 使用事件Using events
// - 使用类型提供程序的Database访问Database access using type providers
// - OData 访问使用提供程序类型OData access using type providers 最后这两个应该是关于数据库的，不会翻译，采用机翻
// ---------------------------------------------------------------
// 整型和基本函数 Integers and basic functions
// ---------------------------------------------------------------
module Integers =
let sampleInteger = 176
/// 对前面那个整数进行一些运算Do some arithmetic starting with the first integer
let sampleInteger2 = (sampleInteger/4 + 5 - 7) * 4
/// 从0到99的数的列表A list of the numbers from 0 to 99
let sampleNumbers = [ 0 .. 99 ]
/// 一个包含0到99的整数以及它们的平方的列表A list of all tuples containing all the numbers from 0 to 99 and their squares
let sampleTableOfSquares = [ for i in 0 .. 99 -> (i, i*i) ]
// 下一行代码打印了一个包含元组的列表，用%A进行通用输出The next line prints a list that includes tuples, using %A for generic printing
printfn "The table of squares from 0 to 99 is:\n%A" sampleTableOfSquares
module BasicFunctions =
// 用“let”关键字定义一个函数，该函数输入一个整数并返回一个整数Use 'let' to define a function that accepts an integer argument and returns an integer.
let func1 x = x*x + 3
// 定义时函数参数可以加括号也可以不加Parenthesis are optional for function arguments
let func1a (x) = x*x + 3
/// 使用这个函数，用“let”获取返回值Apply the function, naming the function return result using 'let'.
/// 变量的类型时从函数的返回类型推断出来的The variable type is inferred from the function return type.
let result1 = func1 4573
printfn "整数4573的平方加3的结果是%d The result of squaring the integer 4573 and adding 3 is %d" result1
// 如果需要，可以使用“(变量名:类型)”的格式显式地指定类型When needed, annotate the type of a parameter name using '(argument:type)'
let func2 (x:int) = 2*x*x - x/5 + 3
let result2 = func2 (7 + 4)
printfn "对(7+4)应用第一个示例函数的结果是%d The result of applying the 1st sample function to (7 + 4) is %d" result2
let func3 x =
if x < 100.0 then
2.0*x*x - x/5.0 + 3.0
else
2.0*x*x + x/5.0 - 37.0
let result3 = func3 (6.5 + 4.5)
printfn "对(6.5+4.5)应用第二个示例函数的结果是%f The result of applying the 2nd sample function to (6.5 + 4.5) is %f" result3
// ---------------------------------------------------------------
// 布尔值 Booleans
// ---------------------------------------------------------------
module SomeBooleanValues =
let boolean1 = true
let boolean2 = false
let boolean3 = not boolean1 && (boolean2 || false)
printfn "表达式 'not boolean1 && (boolean2 || false)' 的值是%A The expression 'not boolean1 && (boolean2 || false)' is %A" boolean3
// ---------------------------------------------------------------
// 字符串Strings
// ---------------------------------------------------------------
module StringManipulation =
let string1 = "Hello"
let string2 = "world"
/// 用@符号创建一个不转义的字符串Use @ to create a verbatim string literal
let string3 = @"c:\Program Files\"
/// 使用三引号字面意义Using a triple-quote string literal
let string4 = """He said "hello world" after you did"""
let helloWorld = string1 + " " + string2 // 把两个字符串串在一起而且它们之间用空格分开concatenate the two strings with a space in between
printfn "%s" helloWorld
/// 一个由结果字符串的前7个字符组成的字符串A string formed by taking the first 7 characters of one of the result strings
let substring = helloWorld.[0..6]
printfn "%s" substring
// ---------------------------------------------------------------
// 元组（有序值集）Tuples (ordered sets of values)
// ---------------------------------------------------------------
module Tuples =
/// 一个简单的整数元组A simple tuple of integers
let tuple1 = (1, 2, 3)
/// 一个可以交换一个元组中值的顺序的函数A function that swaps the order of two values in a tuple.
/// 快速信息显示出该函数推断出具有泛型类型QuickInfo shows that the function is inferred to have a generic type.
let swapElems (a, b) = (b, a)
printfn "The result of swapping (1, 2) is %A" (swapElems (1,2))
/// 一个由一个整数、一个字符串和一个双精度浮点数组成的元组A tuple consisting of an integer, a string, and a double-precision floating point number
let tuple2 = (1, "fred", 3.1415)
printfn "tuple1: %A tuple2: %A" tuple1 tuple2
// ---------------------------------------------------------------
// 列表和列表处理 Lists and list processing
// ---------------------------------------------------------------
module Lists =
let list1 = [ ] ///一个空的列表 an empty list
let list2 = [ 1; 2; 3 ] /// 3个元素的列表 list of 3 elements
let list3 = 42 :: list2 ///42加入到开头的新列表 a new list with '42' added to the beginning
let numberList = [ 1 .. 1000 ] /// 一个从1到1000整数的列表 list of integers from 1 to 1000
///一个包含了一年所有日期的列表 A list containing all the days of the year
let daysList =
[ for month in 1 .. 12 do
for day in 1 .. System.DateTime.DaysInMonth(2012, month) do
yield System.DateTime(2012, month, day) ]
/// 包含棋盘上黑白方格坐标的列表 A list containing the tuples which are the coordinates of the black squares on a chess board.
let blackSquares =
[ for i in 0 .. 7 do
for j in 0 .. 7 do
if (i+j) % 2 = 1 then
yield (i, j) ]
/// 将numberList里面的数平方，用管道运算符给List.map传递参数 Square the numbers in numberList, using the pipeline operator to pass an argument to List.map
let squares =
numberList
|> List.map (fun x -> x*x)
///计算被3整除的数的平方和 Computes the sum of the squares of the numbers divisible by 3.
let sumOfSquares =
numberList
|> List.filter (fun x -> x % 3 = 0)
|> List.sumBy (fun x -> x * x)
// ---------------------------------------------------------------
// 类Classes
// ---------------------------------------------------------------
module DefiningClasses =
/// 这个类的构造函数有两个参数：dx和dy，都是float型（浮点型）的 注：Vector2D的意思是平面向量 The class's constructor takes two arguments: dx and dy, both of type 'float'.
type Vector2D(dx : float, dy : float) =
///计算这个向量对象被构造的时候的长度 The length of the vector, computed when the object is constructed
let length = sqrt (dx*dx + dy*dy)
//“this”关键字表示对象自己 'this' specifies a name for the object's self identifier.
//在实例方法中，它（指this）必须出现在成员名称之前 In instance methods, it must appear before the member name.
member this.DX = dx
member this.DY = dy
member this.Length = length
member this.Scale(k) = Vector2D(k * this.DX, k * this.DY)
/// Vector2D类的一个实例An instance of the Vector2D class
let vector1 = Vector2D(3.0, 4.0)
///不修改原对象而得到一个新的缩放后的vector对象 Get a new scaled vector object, without modifying the original object
let vector2 = vector1.Scale(10.0)
printfn "Length of vector1: %f Length of vector2: %f" vector1.Length vector2.Length
// ---------------------------------------------------------------
// 泛型类Generic classes
// ---------------------------------------------------------------
module DefiningGenericClasses =
type StateTracker<'T>(initialElement: 'T) = // 'T是这个类的参数类型 'T is the type parameter for the class
///列表中的储存状态 Store the states in a list
let mutable states = [ initialElement ]
///将一个新的元素假如到这个states列表 Add a new element to the list of states
member this.UpdateState newState =
states <- newState :: states // 用“<-”运算符改变这个值 use the '<-' operator to mutate the value
/// 得到这整个列表的历史states Get the entire list of historical states
member this.History = states
///获取最新的状态 Get the latest state
member this.Current = states.Head
/// 这个泛型类的一个int类型的实例，请注意参数的类型是被推导出来的 An 'int' instance of the state tracker class. Note that the type parameter is inferred.
let tracker = StateTracker 10
// 添加状态Add a state
tracker.UpdateState 17
// ---------------------------------------------------------------
// 实现接口 Implementing interfaces
// ---------------------------------------------------------------
///实现IDisposable接口 Type that implements IDisposable
type ReadFile() =
let file = new System.IO.StreamReader("readme.txt")
member this.ReadLine() = file.ReadLine()
//这个类对IDisposable接口的实现 this class's implementation of IDisposable members
interface System.IDisposable with
member this.Dispose() = file.Close()
// ---------------------------------------------------------------
// 数组 Arrays
// ---------------------------------------------------------------
module Arrays =
///空数组 The empty array
let array1 = [| |]
let array2 = [| "hello"; "world"; "and"; "hello"; "world"; "again" |]
let array3 = [| 1 .. 1000 |]
/// 只包含了单词“hello”和“world”的数组An array containing only the words "hello" and "world"
let array4 = [| for word in array2 do
if word.Contains("l") then
yield word |]
/// 按照索引包含了从0到2000中所有偶数的数组An array initialized by index and containing the even numbers from 0 to 2000
let evenNumbers = Array.init 1001 (fun n -> n * 2)
///使用切片表示法提取的子数组 sub-array extracted using slicing notation
let evenNumbersSlice = evenNumbers.[0..500]
for word in array4 do
printfn "word: %s" word
// 用左箭头赋值运算符修改数组元素modify an array element using the left arrow assignment operator
array2.[1] <- "WORLD!"
/// 计算以h开头的 单词长度的总和Calculates the sum of the lengths of the words that start with 'h'
let sumOfLengthsOfWords =
array2
|> Array.filter (fun x -> x.StartsWith "h")
|> Array.sumBy (fun x -> x.Length)
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