While working with F# in either Visual Studio or F# interactive if we try to use functions like print_string will give a compile time error.
This can be avoided by either adding reference to current session in F# interactive window by typing:
> #r "FSharp.PowerPack.dll";;
This way we will be able to execute the code using functions defined in PowerPack.dll however in visual studio it will still show the compile time error.
For resolving this we can put the same statement below #light keyword.
This will not display the error message however a warning message will still be displayed stating the compatibility with OCaml.
This will work fine till the time we are working in .fsx file however will give error once you try to build your application. For resolving this FSharp.PowerPack needs to be added to Project Reference which can be found in .Net tab.