Scripting with FSharp

13 October 2020

Updated: 23 December 2025

Before you can use the following, you will need the .NET Core SDK installed

Open the F# Interactive Console

To open an F# interactive console using the dotnet CLI. You can run the following command:

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dotnet fsi

Note that to end statements/execute in the F# Interactive console use ;; at the end of a line or section of code

Once in the console, running #help;; from the fsi console to view the help menu, and #quit;; to quit the interactive session

Additionally, you can write multi-line F# code as well as just single line expressions. Each expression should be terminated with ;;. For example, you can write a function that will print some data into the console:

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let printer s =
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    printfn s
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;;

Next, you can call the function with:

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printer "Hello World";;

Which will execute the above code and output Hello World

Run an F# Script

F# scripts can be run using the dotnet fsi command as well, followed by the path to an F# script file:

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dotnet fsi ./myscript.fsx