>Without type annotations and checked structured data for everything I guess this problem you mention must be Clojure-specific, because in Common Lisp you can

>Without type annotations and checked structured data for everything I guess this problem you mention must be Clojure-specific, because in Common Lisp you can declare the data types of the input parameters and all return parameters, and have the compiler (i.e. SBCL) do static type checking; also the compiler can tell you which data types are accepted and returned by your function, by use of the "describe" function. Furthermore, you can define your own types, structs, and classes, and the declarations (and static type checks) will work with them as well.