Most useful Clojure one-liners for reference, sanity and general information need of beginning developers.

inspect.clj

;; Note: for the best result/experience you should download LightTable at www.lighttable.com
;; Open the program, press [^-Space] (Control-Space) and type "Insta" then click/press [Return] to open one and paste this in

;; Macro to define/create namespace and bind neatly only the required functions (explicit use of :refer key)
(ns clj-no.de
  ^{:doc "Namespace and directives for easy inspection of symbols, hash-maps, namespaces and so on."
    :author "Rob Jentzema"
    :version "0.01"}
  
  ;; These provide us with easy access to some very useful functions
  (:require [clojure.repl :as repl :refer [doc source meta dir]]
            [clojure.pprint :as pprint :refer [pprint print-table]]
            [reflect :as reflect :refers [r]]))

;; Now use as you see fit. (println) (pprint) (print-table) will show in the green/blue bottom window that you need to expand.


;; Automatic promotion in Clojure is possible and desirable since the primary focus is first correctness of numerical values and  then raw speed. This *will always* happen so keep it in mind and accommodate this certainty in your code.

(def clueless 9)
(class clueless) ; it used to be inteyer but now 9 is
(class (+ clueless 9000000000000000000))
(class (+ clueless 90000000000000000000)) ; add and remove zeros
(comment "In this instarepl, notice the datatype change from Long to BigInt and back")
(class (+ clueless 9.0)) ; precision

;; Underflow is the inverse of overflow and equally dangerous, it occurs in floating points
(float 0.00000000000000000000000000000000000000000000000000000000000000000000000000001)
;=> 0.0

1.0+E430
;=> 0.0

;; Be wary of rounding errors! One way to introduce them is by working with doubles and floats

;; Some meta stuff
(source meta)
(doc find-doc)
; (print-doc find-doc) ; deprecated?
; (struct) (defstruct) ; deprecated! use map!

(isa? String "string")
(identical? 'goat 'goat)

(def x (:members (reflect clojure.lang.BigInt)))
(def r (reflect *in*))
(def y (reflect not=))

(print-table [:name :type :flags] (sort-by :name x))

;(apply vector (take 1024 (repeat nil)))