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Ligne 230 : |
Ligne 230 : |
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| = Compilation order = | | = Compilation order = |
| <filebox fn='MyProject.fsproj'> | | <filebox fn='MyProject.fsproj' lang='xml'> |
| <ItemGroup> | | <ItemGroup> |
| <Compile Include="File2.fs" /> | | <Compile Include="File2.fs" /> |
Version du 28 septembre 2022 à 16:31
Command line
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dotnet fsi # start F# Interactive
dotnet fsi script.fsx # run script.fsx
dotnet new console -o fsharp1 -lang f#
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let s = "value"
printfn "text %A text" s
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Format
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Type
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%A |
any
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%s |
string
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%i |
integer
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%b |
boolean
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for
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for i in [1..3] do
printfn "%A" i
for i = 1 to 3 do
printfn "%A" i
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while
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let mutable keepRunning = true
while keepRunning do
// ...
keepRunning <- false
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match
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let x = 2
let result =
match x with
| 1 -> "one"
| 2 -> "two"
| 3 | 4 -> "soon implemented" // 3 or 4
| _ -> "not implemented"
| y -> $"not implemented for {y}"
// pattern matching function syntax
let numberToWord = function
| 1 -> "one"
| 2 -> "two"
| _ -> "not implemented"
numberToWord x // "two"
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String
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let s = "abcde"
// slice
s[1..3] // "bcd"
// triple-quote string allows to use double-quote within the string
let s = """<tag attribute="value" />"""
// concat strings
let sb = StringBuilder()
sb.Append("abc") |> ignore
sb.Append("def") |> ignore
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Collection
List
Ordered, immutable, series of elements of the same type.
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let list1 = [1; 2; 3]
let list2 = [1..5] // [1; 2; 3; 4; 5]
let list3 = [0..2..10] // [0; 2; 4; 6; 8; 10]
let list4 = [for x in 1..5 -> x*x] // [1; 4; 9; 16; 25]
// elements in lists are not mutable
// cons operator
0 :: list1 // create a new list with 0 at the head [0; 1; 2; 3]
// extract head and tail
let head :: tail = list1 // head: 1, tail: [2; 3]
// concatenate operator
list1 @ [4; 5] // create a new list [1; 2; 3; 4; 5]
List.sum(list1) // 6
List.fold (+) 0 list1 // 6 - aggregate
List.iter (fun x -> printfn "%A" x) list1 // 1 2 3
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Array
Fixed-sized, zero-based, mutable collectionof consecutive elements of the same type.
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let myArray = [|1; 2; 3|]
// elements in arrays are mutable
myArray[1] <- 4 // [|1; 4; 3|]
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Map
Set
Immutable Dictionary
Composite data type
Tuple
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let tuple1 = (1, "one")
let (a, b) = tuple1 // a: 1, b: "one"
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Record
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type Item = { Id: int; Name: string; }
let item1 = { Id = 1; Name = "one" }
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Function
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let add x y = x + y
add 1 2 // 3
let myFunction param1 param2 =
let result = param1 + param2
result
// let myFunction (param1: int) (param2: int) : int = ...
myFunction 1 2 // 3
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Unit
Function which doesn't return any value.
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let myUnit (param1: int) (param2: int) =
let result = param1 + param2
printfn "%i" result
() // useless because printfn is already a unit
myUnit 1 2 // 3
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Convertion
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int "123" // 123
float 123 // 123.0
string 123 // "123"
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Console input
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printf "Enter a value: "
let input = Console.ReadLine()
printfn "Entered value: %s" input
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.vscode/launch.json
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{
"configurations": [
{
"console": "integratedTerminal" // // switch from internalConsole to integratedTerminal to allow console input in VS code
}
]
}
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Use binding for disposable object
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use file = File.CreateToText("file.txt")
// Dispose will be called when binding goes out of the scope
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Module
Équivalent to a C# static class.
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// nested module
module Math =
let add x y = x + y
let sub x y = x - y
let v = Math.add 1 2
open Math
let v = add 1 2
// top level module (no =, no indentation, in a separate file)
module Math
let add x y = x + y
let sub x y = x - y
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Module Design Pattern
Separate the definition of data and the behaviors.
DomainTypes.fs
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namespace Finance
module DomainTypes =
type Transaction =
{ Id: int; Amount: float}
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Transaction.fs
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namespace Finance
module Transaction =
let create id amount =
{ Id = id; Amount = amount }
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Execute a shell command
Compilation order
MyProject.fsproj
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<ItemGroup>
<Compile Include="File2.fs" />
<Compile Include="File1.fs" />
</ItemGroup>
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Dev env
- VScode
- Ionide for F# extension → intellisense
- fantomas-fmt → format F#
Create launch and tasks
- Disable the Ionide for F# extension
- Run → Run Without Debugging
- Select environment: .NET 5+ and .NET Core (this create the launch.json file)
- Open launch.json → Add Configuration → .NET: Launch .NET Core Console App
- Fill target-framework = net6.0 and project-name = myproject
- Run → Run Without Debugging
- Configure Task → Create tasks.json file from template → Select a Task Template: .NET Core