Introduce variadic _compose_ in ch05 and fallback to simple _compose2…

…_ for reasonning

Close #443
Close #447

ch05.md

@@ -5,7 +5,14 @@
 Here's `compose`:
 
 ```js
-const compose = (f, g) => x => f(g(x));
+const compose = (...fns) => (...args) => fns.reduceRight((res, fn) => [fn.call(null, ...res)], args)[0];
+```
+
+... Don't be scared! This is the level-9000-super-Saiyan-form of _compose_. For the sake of reasoning, let's drop the variadic implementation and consider a simpler form that can compose two functions together. Once you get your head around that, you can push the abstraction further and consider it simply works for any number of functions (we could even prove that)!
+Here's a more friendly _compose_ for you my dear readers:
+
+```js
+const compose2 = (f, g) => x => f(g(x));
 ```
 
 `f` and `g` are functions and `x` is the value being "piped" through them.