Getting Started

Reading

In order to read Transit encoded JSON you need to construct a reader:

(ns try-transit
  (:require [cognitect.transit :as t]))

(def r (t/reader :json))

Currently :json is the only type of reader available. Given a a reader you can invoke cognitect.transit/read.

For example reading a vector:

(def v (t/read r "[1,2,3]")) ;; [1 2 3]

And reading a map:

(def m (t/read r "{\"~:foo\":\"bar\"}")) ;; {:foo "bar"}

Writing

Like reading, writing is fairly straightforward. Constructing a writer looks very much like constructing a reader:

(ns try-transit
  (:require [cognitect.transit :as t]))

(def w (t/writer :json))

Once you've constructed a writer you can invoke cognitect.transit/write to encode values.

For example writing a vector:

(t/write w [1 2 3]) ;; "[1,2,3]"

And writing a map:

(t/write w {:foo "bar"}) ;; "[\"^ \",\"~:foo\",\"bar\"]"

Maps get written out as JSON arrays as this form is more efficient for decoding. For debugging purposes it's useful to construct a verbose writer:

(def wv (t/writer :json-verbose))

And now the result of writing map-like values is easier to read:

(t/write wv {:foo "bar"}) ;; "{\"~:foo\":\"bar\"}"

This will return the string "{\"~:foo\":\"bar\"}".

Writing Custom Values

Being able to easily write out graphs of ClojureScript values is one the big benefits of transit-cljs. transit-cljs will recursively encode graphs of values and Transit ground values like integers and dates need no special treatment.

To demonstrate this lets define some simple geometry primitives:

(deftype Rect [orgiin size])
(deftype Point [x y])
(deftype Size [width height])

(def arect (Rect. (Point. 0 0) (Size. 150 150)))