Well both. Also in Clojurescript. Clojure's nil punning and Java's Null Pointers are an unholy alliance here. But a type system like Elm solves the problem b

Well both. Also in Clojurescript. Clojure's nil punning and Java's Null Pointers are an unholy alliance here. But a type system like Elm solves the problem before it ever gets to JavaScript for example.