let vs def in clojure

Question

I want to make a local instance of a Java Scanner class in a clojure program. Why does this not work:

; gives me:  count not supported on this          


        

Answer 1

The syntax for them is different, even if the meanings are related.

let takes a list of bindings (name value pairs) followed by expressions to evaluate in the context of those binding.

def just takes one binding, not a list, and adds it to the global context.