It's statically typed and inferred.

With regards to your example, the print/printfn (equivalent of Write/WriteLine) functions are a bit funny in F#. They don't actually take bound string values directly. You need to specify the type (which could be a string, a number, obj, etc)

https://learn.microsoft.com/en-us/dotnet/fsharp/language-ref...

F# is a statically typed language with gradual typing and full type inference.

Given

  let hello value =
      printfn "%A" value
    
  hello "world"
  hello 2

The binding "hello" has "'a -> unit" signature where 'a is a generic argument it accepts because the "printfn" binding with a given format specifier is generalized the same way and an unconstrained 'T (here 'a) is the most narrow type inferred for "hello".

> with gradual typing

Isn't gradual typing widely understood to mean "gradual between static and dynamic", which F# certainly isn't?