README.md

compact-clj

There's no sense in being precise when you don't even know what you're talking about.

• John von Neumann

A library that gives hints to shorten code, based on clj-kondo.

Introduction

Compact-clj is a rule-based code compressor. It uses clj-kondo hooks to attach rules to clojure.core functions. These rules hint at how to shorten the given code.

The rules may propose logically equivalent changes. Thus, you should be careful with compression if you require conversion to boolean.

Getting started

The easiest way to get started is to add this project to your ~/.clojure/deps.edn file.

{:deps
 {compact-clj/compact-clj {:local/root "*path-to-compact-clj*"}}}

You might need to ignore this in your git projects, if you are the only one using it.

Rules

=

;; = -> true?
(= x true) -> (true? x)
;; = -> nil?
(= x nil) -> (nil? x)
;; = -> empty?
(= 0 (count coll)) -> (empty? coll)
;; remove duplicates in =
(= x x y) -> (= x y)

-

;; - -> inc
(- n -1) -> (inc n)
;; - -> dec
(- n 1) -> (dec n)

+

;; remove nested ands
(+ (+ x y) z) -> (+ x y z)
;; + -> inc
(+ n 1) -> (inc n)
;; + -> dec
(+ n -1) -> (dec n)

and

;; remove nested ands
(and (and x y) z) -> (and x y z)
;; and -> every?
(and (f x) (f y)) -> (every? f [x y])

assoc

;; remove nested assocs
(assoc (assoc m :a x) :b y) -> (assoc m :a x :b y)
;; assoc -> assoc-in
(assoc m :a (assoc (:a m) :b x)) -> (assoc-in m [:a :b] x)
;; assoc -> update
(assoc m k (f (k m))) -> (update m k f)

comp

;; remove nested comps
(comp (comp f g) h) -> (comp (comp f g) h)

conj

;; remove nested conjs
(conj (conj coll x) y) -> (conj coll x y)

filter

;; filter -> remove
(filter (complement f) coll) -> (remove f coll)
(filter #(not (f %)) coll) -> (remove f coll)
;; filter -> keep
(filter some? (map f coll)) -> (keep f coll) 

first

;; first -> ffirst
(first (first coll)) -> (ffirst coll)
;; first -> second
(first (next coll)) -> (second coll)

get

;; get -> kw
(get m :a x) -> (:a m x)

if

;; if -> if-not
(if (not t) x y) -> (if-not t x y)
;; if -> when
(if t x nil) -> (when t x)
;; if -> boolean
(if t true false) -> (boolean t)
;; if -> not
(if t false true) -> (not t)
;; if -> cond->
(if t (f x) x) -> (cond-> x t (f))
;; move if inside
(if t (f x y) (f z y)) -> (f (if t x z) y)
;; if -> or
(if x x y) -> (or x y)

into

;; into -> set
(into #{} [x y z]) -> (set [x y z])
;; into -> vec
(into [] '(x y z)) -> (vec '(x y z))

let

;; let -> doto
(let [x y] (f x) (g x) x) -> (doto y (f) (g))
;; let -> when-let
(let [x y] (when x (f x))) -> (when-let [x y] (f x))
;; let -> if-let
(let [x y] (if x (f x) z)) -> (if-let [x y] (f x) z))

map

;; remove nested maps
(map f (map g coll)) -> (map (comp f g) coll)

max

;; remove nested maxs
(max (max x y) z) -> (max x y z)

min

;; remove nested mins
(min (min x y) z) -> (min x y z)

not

;; not -> not=
(not (= x y)) -> (not= x y)
;; not -> not-any?
(not (some f coll)) -> (not-any? f coll)
;; not -> identity
(not (not x)) -> (boolean x)
;; not -> not-every?
(not (every? f coll)) -> (not-every? f coll)
;; not -> seq
(not (empty? coll)) -> (seq coll)
;; not -> odd?
(not (even? n)) -> (odd? n)
;; not -> even?
(not (odd? n)) -> (even? n)
;; not -> some?
(not (nil? x)) -> (some? x)
;; not -> empty?
(not (seq coll)) -> (empty? coll)

or

;; remove nested ors
(or (or x y) z) -> (or x y z)
;; or -> some
(or (f x) (f y)) -> (some f [x y])
;; or -> get
(or (:a x) y) -> (:a x y)
;; or -> contains?
(or (= x y) (= x z)) -> (contains? #{y z} x)

vec

;; vec -> mapv
(vec (map f coll)) -> (mapv f coll)
;; vec -> filterv
(vec (filter pred coll)) -> (filterv pred coll)"

when

;; when -> when-not
(when (not x) y) -> (when-not x y)
;; when -> not-empty
(when (seq coll) coll) -> (not-empty coll)

when-let

;; when-let -> when-first
(when-let [x (first xs)] (f x)) -> (when-first [x xs] (f x))