Meet Duck Typer: your new duck typing friend

The Ruby language leans on duck typing rather than formal interfaces. “If it walks like a duck and quacks like a duck, it’s a duck.” bodies = [poem, essay, case_study, user_manual].map(&:body) These objects come from different classes but all respond to body, so you can treat them uniformly. That’s informal polymorphism: no type annotations, no ceremony. Duck typing is great, but what I miss is enforcement. If one class implements a method and another forgets to, I want something to complain.