Void

Nil is an information representing the absence of information.

This leads to puzzling shenanigans:

;; This is an empty collection, a perfectly normal phenomenon:

[]

;; It contains nothing.

;; This is collection containing something that is nothing:

[nil]

;; Sometimes it is not what we want.

;; This is a map containing something that is nothing, nowhere:

{nil nil}

;; This is seldom what we want.

This small library proposes macros and functions for interacting with nil under various circumstances. Most notably, it considers that nothing is nothing as the following few examples demonstrate.

Usage

Meditate and reflect on the full API.

Some Socratic excerpts :

(require '[dvlopt.void :as void])


(void/assoc {}
            :a 42
            :b nil)

;; => {:a 42}


(void/update {:a 42
              :b 42}
             :b
             (fn [x]
               nil))

;; => {:a 42}


(void/dissoc-in {:a {:b {:c {:d 42}}
                     :e 42}}
                [:a :b :c :d])

;; => {:a {:e 42}}


(void/update-in {:a {:b {:c {:d 24}}
                     :e 42}}
                [:a :b :c :d]
                (fn [x]
                  (when (= x
                           42)
                    x)))

;; => {:a {:e 42}}


(void/merge {:a 42
             :b 42}
            {:b nil
             :c 42})

;; => {:a 42
;;     :c 42}


(void/dmerge {:a {:b {:c {:d 42}}
                  :e 42}}
             {:a {:b {:c {:d nil}}
                  :f 42}})

;; => {:a {:e 42
;;         :f 42}}


(void/prune {:a 42
             :b {:c 42
                 :d nil
                 :e {:f {:g nil}}}})

;; => {:a 42
;;     :b {:c 42}}

Run tests:

$ ./bin/kaocha

License

Copyright © 2018 Adam Helinski

Distributed under the Eclipse Public License either version 1.0 or (at your option) any later version.