No Let, No Rec, No Problem: A Gentler Introduction to the Y and Z Combinators

▤ Summary

This article explains how the Y and Z combinators work by using JavaScript factorial examples. It starts with ordinary recursion, then shows why direct recursion, mutual recursion, and declarations are not allowed in the challenge. From there, it builds the idea of self-application and fixed points, and shows how Y and then Z create recursion without explicit self-reference. The article ends with a working anonymous-function version that calculates factorial in JavaScript under eager evaluation.

▦ Linked Companies