# What exactly is #lang **URL:** \ **Category:** Questions & Answers\ **Tags:** question\ **Created:** [January 30, 2023, 11:34am UTC](https://racket.discourse.group/t/what-exactly-is-lang/1675 "2023-01-30T11:34:10Z")\ **Posts on this page:** 5\ **Page:** 1
**Author:** ![Panadestein](https://yyz2.discourse-cdn.com/free1/user_avatar/racket.discourse.group/panadestein/32/949_2.png) [@Panadestein](https://racket.discourse.group/u/Panadestein)\ **Post date:** [January 30, 2023, 11:34am UTC](https://racket.discourse.group/t/what-exactly-is-lang/1675/1 "2023-01-30T11:34:10Z")
Hi, very basic question here. What is the correct name of "#lang" in Racket ? Is it a "reader form", a "directive", a "reader macro", or something else? ---
**Author:** ![soegaard](https://yyz2.discourse-cdn.com/free1/user_avatar/racket.discourse.group/soegaard/32/19_2.png) [@soegaard](https://racket.discourse.group/u/soegaard)\ **Post date:** [January 30, 2023, 12:05pm UTC](https://racket.discourse.group/t/what-exactly-is-lang/1675/2 "2023-01-30T12:05:49Z")
From [1.3 The Reader](https://docs.racket-lang.org/reference/reader.html) > lang starts a reader extension use; see [Reading via an Extension](https://docs.racket-lang.org/reference/reader.html#%28part._parse-reader%29) ---
**Author:** ![Panadestein](https://yyz2.discourse-cdn.com/free1/user_avatar/racket.discourse.group/panadestein/32/949_2.png) [@Panadestein](https://racket.discourse.group/u/Panadestein)\ **Post date:** [January 30, 2023, 12:09pm UTC](https://racket.discourse.group/t/what-exactly-is-lang/1675/3 "2023-01-30T12:09:27Z")
Thanks for the reply! Exactly in this section, they refer to `#reader` and `#lang` as "reader forms", or simply "forms". That's why I asked. I guess the former is the right name. ---
**Author:** ![robby](https://yyz2.discourse-cdn.com/free1/user_avatar/racket.discourse.group/robby/32/7_2.png) [@robby](https://racket.discourse.group/u/robby)\ **Post date:** [January 30, 2023, 2:06pm UTC](https://racket.discourse.group/t/what-exactly-is-lang/1675/4 "2023-01-30T14:06:46Z")
That answer is a technically correct answer, given a deep understanding of the guts of Racket, but typically one encounters `#lang` at the start of a file and it is more simply (and still accurately) thought of as a declaration of the language of that file. One could say that the parser for Racket is simply checking for `#lang ` and then handing it off to some more specific language to continue parsing (and expansion and compilation, etc) from there. ---
**Author:** ![bremner](https://avatars.discourse-cdn.com/v4/letter/b/aca169/32.png) [@bremner](https://racket.discourse.group/u/bremner)\ **Post date:** [January 30, 2023, 2:38pm UTC](https://racket.discourse.group/t/what-exactly-is-lang/1675/5 "2023-01-30T14:38:18Z")
Robby Findler via Racket Discussions [notifications@racket.discoursemail.com](mailto:notifications@racket.discoursemail.com) writes: > That answer is a technically correct answer, given a deep > understanding of the guts of Racket, but typically one encounters > `#lang` at the start of a file and it is more simply (and still > accurately) thought of as a declaration of the language of that > file. One could say that the parser for Racket is simply checking for > `#lang ` and then handing it off to some more specific language to > continue parsing (and expansion and compilation, etc) from there. For something in between these two answers, see ``` https://docs.racket-lang.org/guide/languages.html ``` I was happy to see this material added to the guide (at least I never noticed it before). I have yet to follow it through and see if I can answer my own question about using brag as a module language inlined in a file by calling #reader. d