gistfile1.ml

   let rec valueFor (property:AType) : obj = 
        match property.Type with
        | AString           -> box property.Name
        | AnInt             -> box 0
        | ADouble           -> box 0.0
        | ABoolean          -> box false
        | ADateTime         -> box DateTime.MinValue
        | AClass            -> box <| build property.Type
        | _                 -> box <| new obj()                
    and build =
            log >>
            getShortestConstructor >>
            invokeWith (getParameters >> Array.map (fun p -> valueFor { Type = p.ParameterType; Name = p.Name })) >>
            andApply (fun t -> t |> getWriteableProperties  |> Array.iter (fun p -> p.SetValue(t, valueFor {Type = p.PropertyType; Name = p.Name}, null))) 

This is the error:
Warning	4	This and other recursive references to the object(s) being defined will be checked for initialization-soundness at runtime through the use of a delayed reference. This is because you are defining one or more recursive objects, rather than recursive functions. This warning may be suppressed by using #nowarn "40" or --nowarn 40.	C:\mark\Builder\Builder.fs	42	62	Builder

the 'valueFor' function call on the 'invokeWith' line gets underlined as being the problematic bit.

If I define it like this there's no such error:

   let rec valueFor (property:AType) : obj = 
        match property.Type with
        | AString           -> box property.Name
        | AnInt             -> box 0
        | ADouble           -> box 0.0
        | ABoolean          -> box false
        | ADateTime         -> box DateTime.MinValue
        | AClass            -> box <| build property.Type
        | _                 -> box <| new obj()                
    and build (t: Type) =
            getShortestConstructor t |>
            invokeWith (getParameters >> Array.map (fun p -> valueFor { Type = p.ParameterType; Name = p.Name })) |>
            andApply (fun t -> t |> getWriteableProperties  |> Array.iter (fun p -> p.SetValue(t, valueFor {Type = p.PropertyType; Name = p.Name}, null)))