Question

I created a new F# library with say the following expressions:

module Module1

let x =  2 + 2

When trying to run this, I get an error

Unexpected start of structured construct in definition. Expected '=' or other token.

Answer 1

When you say “run”, do you mean select all -> ALT + ENTER to send to FSI? If so, I think that is your issue. FSI doesn’t handle file-level module declarations. You need to either not select module Module1 when you send it to FSI, or change it to a module expression:

module Module1 =
    let x = 2 + 2