Hello World, the most famous and basic computing problem! However, after implementing it in several languages, I realized that this problem should be solved once for many languages instead of having to be rewritten time and time again. We clearly need a compiler for Hello World programs.
We start by writing what we believe to be Hello World in untyped lambda calculus. Since modern operating systems lack an interpreter by default, we had to write one here. Unfortunately, evaluating nominal lambda calculus is hard, so we simplify the problem by transforming it into De Bruijn form, and then evaluate that. This allowed checking that the program is indeed Hello World. We can finally compile this lambda calculus version to a SK based one, which is easy to evaluate in many practical langauges, such as not Java.
You can view the generated Hello Worlds in the helloworld subdirectory, or
generate them yourself by running scripts/generate-hello-worlds.