F# For Dummys - Day 3 New Program

Today we create a F# program and run it on local environment
for a web editor user, your online environment will process the same procedure to run your f# code

1、open a command window (input 'cmd' in search text input, or press Win button then input 'cmd')

2、input command below

dotnet new console -lang F# -o MyFSharpApp

this command will create a program named MyFSharpApp in F#

open your file explorer, open the folder created in last step, let's check what it contains

the only file you need to care about now is the f# source code file which end with .fs
open our source code file(Program.fs) in notepad

3、go back to our command window, input

cd MyFSharpApp

it will change directory (cd) to MyFSharpApp dir

4、run your code

dotnet run

output

5、check our app dir again

we got a new dir named 'bin', let's see what's inside

it contains the compile output, MyFSharpApp.exe is our application file, you can ignore other output files for right now

6、make the output window wait, notice the web browser environment don't support this step

let's change our source code a little bit like below

open System
printfn "Hello from F#"
Console.ReadLine()

and run it again

dotnet run

go to the comile output dir: bin/Debug/net8.0
double click our new application file: MyFSharpApp.exe

you will see the same result like in the command window, right

actually in the command window, it also calls MyFSharpApp.exe at backend, so it's the same result as you execute the exe file by double click it

if you wonder what is compile?

a simple way to explain:

it's a translator who translate your source code to Intermediate Language (IL) code, the .NET runtime understand IL, the JIT compiler will translate IL into machine code that CPU only understand

well, it seems not that simple, we don't dive deep here