To be evaluated using my prolog lambda calculus evaluator:
https://gist.github.com/madidier/bfb9a936550c92d7d63fea49da90253d

Left  = x -> l -> r -> l(x),
Right = x -> l -> r -> r(x),
Id    = x -> x,
Const = a -> b -> a,

Main = [Right, "lol", [Const, ""], Id],

parse(Main, AST), deepEval(AST, :Res), writeln(Res).