; Comments start with a semicolon.
; Anything after the semicolon is ignored.

;;;;;;;;;;;;;;;;;;;
;;; Basic Types ;;;
;;;;;;;;;;;;;;;;;;;

nil         ; also known in other languages as null

; Booleans
true
false

; Strings are enclosed in double quotes
"hungarian breakfast"
"farmer's cheesy omelette"

; Characters are preceded by backslashes
\g \r \a \c \e

; Keywords start with a colon. They behave like enums. Kind of
; like symbols in Ruby.
:eggs
:cheese
:olives

; Symbols are used to represent identifiers. 
; You can namespace symbols by using /. Whatever precedes / is
; the namespace of the symbol.
spoon
kitchen/spoon ; not the same as spoon
kitchen/fork
github/fork   ; you can't eat with this

; Integers and floats
42
3.14159

; Lists are sequences of values
(:bun :beef-patty 9 "yum!")

; Vectors allow random access
[:gelato 1 2 -2]

; Maps are associative data structures that associate the key with its value
{:eggs        2
 :lemon-juice 3.5
 :butter      1}

; You're not restricted to using keywords as keys
{[1 2 3 4] "tell the people what she wore",
 [5 6 7 8] "the more you see the more you hate"}

; You may use commas for readability. They are treated as whitespace.

; Sets are collections that contain unique elements.
#{:a :b 88 "huat"}

;;;;;;;;;;;;;;;;;;;;;;;
;;; Tagged Elements ;;;
;;;;;;;;;;;;;;;;;;;;;;;

; EDN can be extended by tagging elements with # symbols.

#MyYelpClone/MenuItem {:name "eggs-benedict" :rating 10}

; Let me explain this with a Clojure example. Suppose I want to transform that
; piece of EDN into a MenuItem record.

(defrecord MenuItem [name rating])

; defrecord defined, among other things, map->MenuItem which will take a map
; of field names (as keywords) to values and generate a user.MenuItem record

; To transform EDN to Clojure values, I will need to use the built-in EDN
; reader, clojure.edn/read-string

(clojure.edn/read-string "{:eggs 2 :butter 1 :flour 5}")
; -> {:eggs 2 :butter 1 :flour 5}

; To transform tagged elements, pass to clojure.edn/read-string an option map
; with a :readers map that maps tag symbols to data-reader functions, like so

(clojure.edn/read-string
    {:readers {'MyYelpClone/MenuItem map->MenuItem}}
    "#MyYelpClone/MenuItem {:name \"eggs-benedict\" :rating 10}")
; -> #user.MenuItem{:name "eggs-benedict", :rating 10}