F# Interactive is a Read-Eval-Print-Loop (REPL), which is an ad-hoc environment that lets you experiment with F# code, running the code as soon as you write it without leaving the editor.
You can either:
open the F# Interactive tool window () and write code directly in there
select one or more lines of code in the editor and press Ctrl+\ to send them to the F# Interactive window
F# Interactive will attempt to compile your code and execute it if successful. Otherwise the interpreter will return the error messages.
The F# Interactive tool window allows you to:
clear its editor
copy any recently executed command:
To have the copied command executed at once, uncheck Copy recent commands to Interactive editor in the F# Interactive settings.