Naming - local scope

Local names in functions

You can define names for things within the scope of a function using the let function.

Example

You can use the let function to define a simple expression, for which everything will go out of scope once it has been evaluated

(let [local-name "some value"])
(let [minutes-in-a-day (* 60 60 24)])

You can also use let inside a function to do something with the arguments passed to that function. Here we calculate the hourly-rate from a yearly salary, returning the calculated-rate.

(defn hourly-rate [yearly-salary weeks-in-year days-in-week] (let [calculated-rate (/ yearly-salary weeks-in-year days-in-week)] calculated-rate))

(hourly-rate 60000 48 5)

## Local names in data structures

  When defining a map you are creating a series of key value pairs.  The key is essentially a name that represents the value it is paired with.  Keys are often defined using a `:keyword`.

```clojure
  {:radius 10, :pi 22/7 :colour purple}

  (def my-circle {:radius 10, :pi 22/7 :colour purple})

Fixme This is incorrect, as a Clojure keyword type (a name starting with :) have global scope within a namespace. If the keys were strings, then they would have the scope of just the collection.