Searchable: flip the order of the arguments of the methods
List: flip the order of arguments of some methods
Foldable: flip the arguments of some methods
README: make the overview narrower so we can see it all
Core: add `are` to make it prettier when there are many data types.
Functional: add `infix` and use it to implement `on`
Sandbox: remove tuple implementation (posted to comp.lang.c++.moderated)