8.12
choose-lang: Pick #lang at read-time
| #lang choose-lang | package: choose-lang |
Meta-language for selecting a #lang as the module is initially read.
For example, the following module raises a type error if the environment variable CHOOSE_TYPES is set, and otherwise ignores the type annotation.
#lang choose-lang (if (getenv "CHOOSE_TYPES") typed/racket typed/racket/no-check) (: f Integer) (define f 'foo)