mfikes

If you are curious about the types inferred by ClojureScript, it is easy to get some insight using a macro:

(defmacro inferred-type [form]
  `'~(cljs.analyzer/infer-tag &env
       (cljs.analyzer/no-warn (cljs.analyzer/analyze &env form))))

This is the kind of dev-time macro you could refer using the new user.cljs feature.

comnik

{:deps
 {org.clojure/clojure      {:mvn/version "1.9.0"}
  com.datomic/datomic-free {:mvn/version "0.9.5697"}}}

robert-stuttaford

(require '[cljs.build.api :as api]
         '[clojure.string :as string]
         '[figwheel-sidecar.repl-api :as figwheel]
         '[figwheel-sidecar.components.nrepl-server :as figwheel.nrepl])

(def source-dir "src")

(def compiler-config
  {:main          'app.main
   :output-to     "target/app.js"

comnik

(defn relate [& pairs]
  (assert (even? (count pairs)) "relate requires an even number of arguments")
  (->> pairs
       (partition 2)
       (map (fn [[k vs]] (map #(hash-map k %) vs)))
       (apply map merge)))


(defn matches-specmap? [specmap m]
  (reduce-kv

stuarthalloway

;; try this form-by-form at a REPL
(require '[clojure.spec.alpha :as s])

;; create an inline DSL to describe the FizzBuzz world
(defmacro divides-by
  [nm n]
  `(s/def ~nm (s/and pos-int? #(zero? (mod % ~n)))))

;; specify FizzBuzz 
(divides-by ::fizz 3)

reborg

Rich Already Answered That!

A list of commonly asked questions, design decisions, reasons why Clojure is the way it is as they were answered directly by Rich (even when from many years ago, those answers are pretty much valid today!). Feel free to point friends and colleagues here next time they ask (again). Answers are pasted verbatim (I've made small adjustments for readibility, but never changed a sentence) from mailing lists, articles, chats.

How to use:

• The link in the table of content jumps at the copy of the answer on this page.
• The link on the answer itself points back at the original post.

Table of Content

jasongilman

Atom Clojure Setup

This describes how I setup Atom for an ideal Clojure development workflow. This fixes indentation on newlines, handles parentheses, etc. The keybinding settings for enter (in keymap.cson) are important to get proper newlines with indentation at the right level. There are other helpers in init.coffee and keymap.cson that are useful for cutting, copying, pasting, deleting, and indenting Lisp expressions.

Install Atom

Download Atom

The Atom documentation is excellent. It's highly worth reading the flight manual.

jlongster

A lot of people mentioned other immutable JS libraries after reading my post. I thought it would be good to make a list of available ones.

There are two types of immutable libraries: simple helpers for copying JavaScript objects, and actual persistent data structure implementations. My post generally analyzed the tradeoffs between both kinds of libraries and everything applies to the below libraries in either category.

Libraries are sorted by github popularity.

Persistent Data Structures w/structural sharing

cgrand

PersistentHashMap benchmark: kvbitmap vs master

results are kvbitmap runtime / master runtime
below 100% kvbitmap is faster
above 100% master is faster

size	assoc!	assoc	get	dissoc	dissoc!
16	84,64%	91,21%	96,56%	99,84%	89,91%
64	80,12%	91,66%	98,66%	104,97%	92,78%
256	89,37%	99,33%	97,59%	111,69%	98,20%

jlongster

  // Simple wrapper to use bootstrap's grid system to position elements side-by-side
  var VerticalFieldsElement = React.createClass({
    render: function() {
      return dom.div(
        { className: 'clearfix' },
        React.Children.map(this.props.children, function(child) {
          if(!child) {
            return child;
          }