Lisp’s Influence on Ruby. Once I wrote users.select { |u|… | by Ian Johnson | Jun, 2026 | Medium

Once I wrote users.select { |u| u.admin? }.map(&:email) and realized I’d written Lisp. Not literally. The parentheses are gone, the prefix notation is gone, the lambdas are syntactic blocks. But the shape of the code (chain a filter onto a transform, ask each element a yes-or-no question with ?, build the result without mutating anything) is Lisp. Ruby just put it in business casual. Matz has said as much. He’s described Ruby’s design as starting from a simple Lisp, stripping out macros and s-expressions, then adding an object system, blocks, and Smalltalk-style methods. The features most Rubyists fall in love with aren’t the object-oriented ones. They’re the functional ones, dressed in friendlier clothes. Here is the list I think about often, and why each one matters.