gistfile1.txt

public interface IDynamoDataAccessLayer
{
  void Save<T>(T entity, string config = null);
  void Save2<T>(T entity);
  void Save3(string entity);
}


let dal =
    Mock<IDynamoDataAccessLayer>()
        .Setup(fun x -> <@ x.Save(any(), any()) @>)
        .Calls<_>(fun x -> printfn "%A" x)
        .Setup(fun x -> <@ x.Save2(any()) @>)
        .Calls<_>(fun x -> printfn "%A" x)
        .Setup(fun x -> <@ x.Save3(any()) @>)
        .Calls<_>(fun x -> printfn "%A" x)
        .Create()

dal.Save(42)  // doesn't work
dal.Save2(42) // doesn't work
dal.Save3("42") // works


// tried this (explicit type for Call<int>) as well, same thing
let dal =
    Mock<IDynamoDataAccessLayer>()
        .Setup(fun x -> <@ x.Save(any(), any()) @>)
        .Calls<int>(fun x -> printfn "%d" x)
        .Setup(fun x -> <@ x.Save2(any()) @>)
        .Calls<int>(fun x -> printfn "%d" x)
        .Setup(fun x -> <@ x.Save3(any()) @>)
        .Calls<_>(fun x -> printfn "%A" x)
        .Create()
        
dal.Save(42)  // doesn't work
dal.Save2(42) // doesn't work
dal.Save3("42") // works

Current Foq (1.7.1) requires explicitly typed arguments in the Setup if you are using Calls, otherwise the Setup produces an instance specialised to obj. This is so that Foq can support multiple Setups with different explicit generic arguments and match them accordingly.
This works in the current version:

type IDynamoDataAccessLayer =
interface
abstract Save<'T> : entity:'T * config:string -> unit
abstract Save2<'T> : entity:'T -> unit
abstract Save3 : entity:string ->unit
end

let dal =
Mock()
.Setup(fun x -> <@ x.Save(It.IsAny(), any()) @>)
.Calls<int*string>(fun x -> printfn "1 %A" x)
.Setup(fun x -> <@ x.Save2(any()) @>)
.Calls(fun x -> printfn "2 %A" x)
.Setup(fun x -> <@ x.Save3(any()) @>)
.Calls(fun x -> printfn "3 %A" x)
.Create()

dal.Save(42, "") // this work
dal.Save2(box 43) // this work
dal.Save3("42") // works