#langversion

Nobody has claimed this yet.

# #langversion

I propose we add `#langversion` to F# scripts.

```fs
#langversion "preview"
let x = () in nameof x;; // :)
```

The existing way of approaching this problem in F# is creating an entire project just to make scripts with `nameof` usable.

```fs

Microsoft (R) F# Interactive version 10.6.0.0 for F# 4.7
Copyright (c) Microsoft Corporation. All Rights Reserved.

For help type #help;;

> let x = () in nameof x;; // :(

let x = () in nameof x;; // :(
--------------^^^^^^

stdin(1,15): error FS0039: The value or constructor 'nameof' is not defined.

>
```

## Pros and Cons

The advantages of making this adjustment to F# are
1. Ability to use new F# features in script files
2. More consistency with actual F#

The disadvantages of making this adjustment to F# are none that I can think of.

## Extra information

Estimated cost (XS, S, M, L, XL, XXL): S

Related suggestions: None

## Affidavit (please submit!)

Please tick this by placing a cross in the box:
* [x] This is not a question (e.g. like one you might ask on [stackoverflow](http://stackoverflow.com)) and I have searched stackoverflow for discussions of this issue
* [x] I have [searched both open and closed suggestions on this site](http://github.com/fsharp/fslang-suggestions/issues) and believe this is not a duplicate
* [x] This is not something which has obviously "already been decided" in previous versions of F#. If you're questioning a fundamental design decision that has obviously already been taken (e.g. "Make F# untyped") then please don't submit it.

Please tick all that apply:
* [x] This is not a breaking change to the F# language design
* [x] I or my company would be willing to help implement and/or test this

Start with the F# Interactive script behavior shown in the issue and review the discussion around adding #langversion. Determine how scripts should select language versions and verify that a script using nameof can enable preview features without creating a project.

Written by the indexing model from the issue text.