Add docs for day 18

Author: Siphalor

18-r/README.md

@@ -0,0 +1,31 @@
+# Day 18: R
+
+## Previous Experiences
+
+None.
+
+## Notes
+
+I heard good things about R of people using it for some university related projects.
+
+But I can't confirm that.
+
+One of the biggest flaws of R is that it is only call-by-value.
+There is literally no simple call-by-reference.
+
+Another thing that comes on top is the whole fuckup that R's lists are.
+Not only you have to index them with `[[i]]` instead of `[i]` (because that gives you a singleton list, for some reason),
+being a key feature of R they're missing a lot of functionality.
+
+For example there is no simple way to insert to a list. There just isn't.
+There exist hacky workarounds with sorting and some indexing magic and there are literally libraries for this but this should really be a core feature.
+
+The whole file inclusion system is just bad and feels on one layer with that of C.
+And we all know how we hated C for `#include`.
+
+R feels like a giant fuckup.
+There might be some useful stuff in it but if you try to do anything that isn't exactly intended by the authors,
+then you'll have to rely on external libraries or prepare for writing lots of utility stuff.
+It feels like a functional language (like Haskell) but without all the stuff that makes functional programming fun.
+
+This was the worst language so far. And yes, this tops Chef.

README.md

@@ -22,3 +22,4 @@ I'll try to choose a different programming language that I am more or less famil
 | [15](15-php)     | [`PHP`](https://en.wikipedia.org/wiki/PHP_(programming_language))           | -                                                                          |
 | [16](16-js)      | [`JavaScript`](https://en.wikipedia.org/wiki/JavaScript)                    | -                                                                          |
 | [17](17-clojure) | [`Clojure`](https://en.wikipedia.org/wiki/Clojure)                          | -                                                                          |
+| [18](18-r)       | [`R`](https://en.wikipedia.org/wiki/R_(programming_language))               | -                                                                          |