Does F# provide any map/dictionary that's not ordered?

I'm observing F#'s Map is always ordered based on its keys. Does F# provide any alternative to an ordered dictionary?

I wanted to ask before using a C# Dictionary as an alternative.

What does FX -> Y mean?

f:x↦y means that f is a function which takes in a value x and gives out y.

What does f stand for in math?

more ... A special relationship where each input has a single output. It is often written as "f(x)" where x is the input value. Example: f(x) = x/2 ("f of x equals x divided by 2")

What does f say about f?

Given a function f, the derivative f' can be used to get important information about f. For instance, f is increasing when f'>0. The second derivative gives useful concavity information.

FSharpx.Collections has the PersistentHashMap, which isn't ordered.