All theorems are proved without using the tactic framework.
Thus, we can define `fin/uint32/uint64` types and their operations
before we define the tactic framework.
This suggestion has been discussed at Slack.
We have decided to use #"c" as notation because we wanted to allow `'`
in the beginning of identifiers like in SML and F*. In particular,
we wanted to allow users to use 'a 'b 'c for naming type parameters
like in SML. However, nobody used this notation. In the Lean standard
library, we are using greek letters for naming type parameters.
So, there is no real motivation for the ugly #"c" syntax.
The idea is to make sure lean doesn't timeout (at reflexivity) when we apply simp or
rewrite in goals such as
(x y : nat) |- x + y + 10000000000 = x + y + 200000000000000
This commit also addresses an issue raised at #1218
