open System

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​

type Temperature = F of int | C of int

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let freezing = F 32

Console.WriteLine("A union: {0}", freezing)

printfn "A union: %A" freezing

​

​

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let rows = [ (1,"a"); (-22,"bb"); (333,"ccc"); (-4444,"dddd") ] 

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// no alignment

printfn "==========================="

for (i,s) in rows do

    printfn "no alignment: |%i|%s|" i s

​

​

// with alignment

printfn "==========================="

for (i,s) in rows do

    printfn " wih alignment: |%5i|%5s|" i s

​

// with left alignment for column 2

printfn "==========================="

for (i,s) in rows do

    printfn "with left align for column 2: |%5i|%-5s|" i s

​

// with dynamic column width=20 for column 1

printfn "==========================="

for (i,s) in rows do

    printfn "with dynamic column width 20 for col1: |%*i|%-5s|" 20 i s 

​

// with dynamic column width for column 1 and column 2

printfn "==========================="

for (i,s) in rows do

    printfn "with dynamic col width for col 1 & col 2: |%*i|%-*s|" 20 i 10 s 

printfn "==========================="    

let pi = 3.14

printfn "float: %f \nexponent: %e \ncompact: %g" pi pi pi 

​

printfn "==========================="

let petabyte = pown 2.0 50

printfn "float: %f \nexponent: %e \ncompact: %g" petabyte petabyte petabyte 

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(* Custom Formatting fonction: *)

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(* Utilisation %t *)

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open System.IO

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//define the function using a closure

let printRand = 

    let rand = new Random()

    // return the actual printing function

    fun (tw:TextWriter) -> tw.Write(rand.Next(1,10))

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//test it

for i in [1..5] do

    printfn "rand = %t" printRand 

​

(* Utilisation %a *) 

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//define the callback function

//note that the data parameter comes after the TextWriter

let printLatLong (tw:TextWriter) (lat,long) = 

    tw.Write("lat:{0} long:{1}", lat, long)

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// test it

let latLongs = [ (1,2); (3,4); (5,6)]

for latLong  in latLongs  do

    // function and value both passed in to printfn

    printfn "latLong = %a" printLatLong latLong  

(* Formattage de dates *)

// function to format a date

let yymmdd1 (date:DateTime) = date.ToString("yy.MM.dd")

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// function to format a date onto a TextWriter

let yymmdd2 (tw:TextWriter) (date:DateTime) = tw.Write("{0:yy.MM.dd}", date)

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// test it

for i in [1..5] do

    let date = DateTime.Now.AddDays(float i)

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    // using %s

    printfn "using ToString = %s" (yymmdd1 date)

    // using %a

    printfn "using a callback = %a" yymmdd2 date

​

​