I'll post my answer later,
I’m trying to stop procrastinating and implement a type checker for Conc.
Never heard of concatenating programming, reading https://evincarofautumn.blogspot.com/2012/02/why-concatenative-programming-matters.html?m=1 now.
You may find the concatenative wiki interesing as well.
I’m fixing issues of Lambdahackers and playing with concatenative programming.