Daily Challenge (188 Part Series)
The kata is inspired by a Stack Overflow question.
It is easy to prove that
f(f(f b)) = f b for all functions
f : bool -> bool. But can you do it in less than 92 characters?
More specifically, your task is to prove the following lemma:
Lemma lemma : forall (f : bool -> bool) (b : bool), f (f (f b)) = f b.
And the size of your solution (including all declarations) should be 91 characters or less.
Want to propose a challenge idea for a future post? Email firstname.lastname@example.org with your suggestions!