add section about scheme-report-environment

docs/docs/lips/environments.md

@@ -42,9 +42,41 @@ In LIPS you can change the environment with `let-env` syntax:
 ;; ==> 30
 ```
 
+## Scheme Report Environments
+Scheme standard provide environments for given version of the [R<sup>n</sup>RS
+specification](/docs/scheme-intro/what-is-lisp#standards) in a form of a function
+`scheme-report-environment`.
+
+You can use this function in LIPS with version 5 and 7 to get R<sup>5</sup>RS or R<sup>7</sup>RS.
+
+**NOTE**: that some of the functions from R<sup>5</sup>RS may have features of R<sup>7</sup>RS since
+some of them got additional arguments. R<sup>n</sup>RS is backward compatible.
+
+You can use this function with `eval` or `let-env`:
+
+```scheme
+(let ((env (scheme-report-environment 7)))
+  (let-env env
+     (display (+ 1 2))))
+;; ==> 3
+(let-env (scheme-report-environment 7)
+  (display (--> "string" (toUpperCase))))
+;; ==> Unbound variable `-->'
+(let-env (scheme-report-environment 7)
+   (write (vector-map + #(1 2 3) #(4 5 6 7))))
+;; ==> #(5 7 9)
+(let-env (scheme-report-environment 5)
+   (write (vector-map + #(1 2 3) #(4 5 6 7))))
+;; ==> Unbound variable `vector-map'
+```
+
+R<sup>5</sup>RS doesn't support `vector-map` that was added in version R<sup>7</sup>RS. The same
+both Scheme versions doesn't support LIPS extensions like [`-->`
+macro](/docs/lips/intro#helper-macros-and-functions).
+
 ## Introspection
 
-Since environments are JavaScript objects you can access it's properties like `__name__` or `__env__`.
+Since environments are JavaScript objects you can access its properties like `__name__` or `__env__`.
 
 ```scheme
 (let ((x 10) (y 20))