Oh wow, Miranda is still using an SK combinator reduction evaluator dating from 1986, in K&R C. It isn't even using supercombinators, which I read about in https://www.microsoft.com/en-us/research/publication/the-imp...

Combinators are fun, but not very fast :-) https://dl.acm.org/doi/10.1145/800087.802798 http://ioccc.org/years.html#1998_fanf