I didn't see the function composition operator in there, I saw a lot of use of the pipe operator (|>), F# does have backwards function composition but it is the << operator. Function composition is >>. You can also define new operators or redefine operators in F#.
The annoying upshot of this is that bitwise operations in F# use three character operators &&&, |||, ^^^, <<<, >>> which is weird coming from an imperative background.
They use this feature for dynamic invocation on the DLR (.NET 4.0), so to invoke foo() dynamically on bar you'd write bar?foo instead of bar.foo
Speaking of regexes and operators, if you're a fan of perl or ruby you can do the following:
let (=~) text pattern = Regex.IsMatch(text,pattern)
or for maximum F# goodness
let (=~) text pattern = Regex.Matches(text,pattern) |> (fun matches -> match matches.Length with 0 -> None | _ -> Some(matches))
