functional programming - 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, reallity gets in the way, and with different inputs, I might not need a certain function, and if that function is computationally expensive, I'd like to not evaluate it if it's not needed.
I found a workaround, using let func _ = ... and calling it with func 1 or whatever, but that feels very non-idiomatic and confusing to the reader.

This boils down to one question: In F#, Is there a proper way to declare a function with zero arguments, without having it evaluated on declaration?

Answer 1

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 ().)