Category "idris"

Proving a simple list function applied four times is the identity

The following video contains a mathematical card trick due to Colm Mulcahy: https://www.youtube.com/watch?v=dHzUQnRjbuM The key operation in the trick is define

How can i convince Idris that my function is covering?

I wrote a function doSomething that takes an open or closed parenthesis and returns a corresponding Int: doSomething : (c : Char) -> {auto isPar : c == '(' |