Using RC4, enter the following in an F# script file:

module MyOps =
    let (>.>) x f = f(x)

let bananas xs =
    xs >.> List.map (fun x -> "bananas")

Expected: Lightbulb comes up, offering to open MyOps.

Actual: No lightbulb.

Note that this affects libraries such as Suave, where you need to open the Suave.Operators namespace to compose routes, and it's not always obvious to people that this is the case.