F# - Function with no arguments?

Question

When thinking in a functional mindset, given that functions are supposed to be pure, one can conclude any function with no arguments is basically just a value.
However,

Answer 1

I think what you want is lazy.

let resource = 
    lazy(
        // expensive value init here
    )

Then later when you need to read the value...

resource.Value

If you never call the Value property, the code inside the lazy block never gets run, but if you do call it, that code will be run no more than once.

Answer 2

The usual idiom is to define the function to take one argument of type Unit (let functionName () = 42). It will then be called as functionName (). (The unit type has only one value, which is ().)