michiakig

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; Ant sim ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;   Copyright (c) Rich Hickey. All rights reserved.
;   The use and distribution terms for this software are covered by the
;   Common Public License 1.0 (http://opensource.org/licenses/cpl.php)
;   which can be found in the file CPL.TXT at the root of this distribution.
;   By using this software in any fashion, you are agreeing to be bound by
;   the terms of this license.
;   You must not remove this notice, or any other, from this software.

;dimensions of square world

daveray

; A REPL-based, annotated Seesaw tutorial
; Please visit https://github.com/daveray/seesaw for more info
;
; This is a very basic intro to Seesaw, a Clojure UI toolkit. It covers
; Seesaw's basic features and philosophy, but only scratches the surface
; of what's available. It only assumes knowledge of Clojure. No Swing or
; Java experience is needed.
;
; This material was first presented in a talk at @CraftsmanGuild in
; Ann Arbor, MI.

yogthos

(ns file-watcher
  (:require [clojure.set :refer [rename-keys]]
            [clojure.java.io :refer [file]])
  (:import
       [java.nio.file
        FileSystems
        Path
        Paths
        StandardWatchEventKinds]))

ptaoussanis

(comment ; Fun with transducers, v2

  ;; Still haven't found a brief + approachable overview of Clojure 1.7's new
  ;; transducers in the particular way I would have preferred myself - so here goes:

  ;;;; Definitions
  ;; Looking at the `reduce` docstring, we can define a 'reducing-fn' as:
  (fn reducing-fn ([]) ([accumulation next-input])) -> new-accumulation
  ;; (The `[]` arity is actually optional; it's only used when calling
  ;; `reduce` w/o an init-accumulator).

fasiha

; Learn Datalog Today (http://www.learndatalogtoday.org) is a great resource for
; reading but its interactive query interface is broken. Below is how we can
; load the same data into a Clojure REPL and play with it using DataScript.
; After running the code below, many/most/all? of the queries on Learn Datalog
; Today should be functional.
;
; Create a new lein project, add `[datascript "0.15.0"]` to `project.clj`'s
; `dependencies`, run `lein deps && lein repl` and copy-paste the following in
; chunks, inspecting the outputs as needed.

cgrand

;; the SET game in clojure.spec
;; inspired by https://github.com/jgrodziski/set-game

(require '[clojure.spec :as s])

(s/def ::shape #{:oval :diamond :squiggle})
(s/def ::color #{:red :purple :green})
(s/def ::value #{1 2 3})
(s/def ::shading #{:solid :striped :outline})
(s/def ::card (s/keys :req [::shape ::color ::value ::shading]))

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

olieidel

(ns yourproject.yourns
  (:require [clojure.java.io :as io]))

(defn delete-directory-recursive
  "Recursively delete a directory."
  [^java.io.File file]
  ;; when `file` is a directory, list its entries and call this
  ;; function with each entry. can't `recur` here as it's not a tail
  ;; position, sadly. could cause a stack overflow for many entries?
  ;; thanks to @nikolavojicic for the idea to use `run!` instead of

bhb

(require '[clojure.spec.gen.alpha :as sgen])

;; original
(defn multimethod-selector
  "Returns a generator that picks one dispatch value from the known
   dispatch values of a multimethod. Defers the lookup of dispatch
   values until sampling time, so any defmethods evaluated after the
   generator is created may still be selected."
  [s]
  #(sgen/bind

robertbraeutigam

public static <T> Stream<T> inCompletionOrder(Collection<CompletableFuture<T>> futures) {
    BlockingQueue<CompletableFuture<T>> queue = new LinkedBlockingQueue<>();
    for (CompletableFuture<T> future: futures) {
        future.whenComplete((value,exception) -> queue.add(future));
    }
    return Stream.generate(noException(queue::take))
        .map(CompletableFuture::join)
        .limit(futures.size());
}