map with fn - anonymous function

TODO::work in progress, sorry

(map (fn [arg] (+ arg 5)) [1 2 3 4 5])

There is a syntactic short-cut for the anonymous function that does not require a name for the arguments

#(+ %1 5)

Adding this into our previous expression we can see that its still quite readable and helps keep the code clean.

(map #(+ arg 5) [1 2 3 4 5])

Hint::Anonymous function name

Anonymous functions do not have an externally referable name, so must be used in-line with an expression.

The fn function can be defined with a name, however, this is only available in the scope of that function definition, the name cannot be used to refer to that function outside of its definition.

Including a name within a fn definition enables the function to call itself, therefore creating an anonymous recursive function.