Switch 'AT&T Park' to 'Oracle Park' on answer sheet

The word "do" seems to be missing in the final koan.

.gitignore

@@ -1,11 +1,206 @@
+*~
 bin
-classes
-lib
 releases
-target
 *.jar
-.DS_Store
-.lein-deps-sum
-.lein-plugins
-.lein-repl-history
 
+# Created by https://www.gitignore.io/api/clojure,osx,linux,windows,leiningen,intellij,eclipse,sublimetext
+
+### Clojure ###
+pom.xml
+pom.xml.asc
+*jar
+/lib/
+/classes/
+/target/
+/checkouts/
+.lein-deps-sum
+.lein-repl-history
+.lein-plugins/
+.lein-failures
+.nrepl-port
+
+
+### OSX ###
+.DS_Store
+.AppleDouble
+.LSOverride
+
+# Icon must end with two \r
+Icon
+
+
+# Thumbnails
+._*
+
+# Files that might appear in the root of a volume
+.DocumentRevisions-V100
+.fseventsd
+.Spotlight-V100
+.TemporaryItems
+.Trashes
+.VolumeIcon.icns
+
+# Directories potentially created on remote AFP share
+.AppleDB
+.AppleDesktop
+Network Trash Folder
+Temporary Items
+.apdisk
+
+
+### Linux ###
+*~
+
+# KDE directory preferences
+.directory
+
+# Linux trash folder which might appear on any partition or disk
+.Trash-*
+
+
+### Windows ###
+# Windows image file caches
+Thumbs.db
+ehthumbs.db
+
+# Folder config file
+Desktop.ini
+
+# Recycle Bin used on file shares
+$RECYCLE.BIN/
+
+# Windows Installer files
+*.cab
+*.msi
+*.msm
+*.msp
+
+# Windows shortcuts
+*.lnk
+
+
+### Leiningen ###
+pom.xml
+pom.xml.asc
+*jar
+/lib/
+/classes/
+/target/
+/checkouts/
+.lein-deps-sum
+.lein-repl-history
+.lein-plugins/
+.lein-failures
+.nrepl-port
+
+
+### Intellij ###
+# Covers JetBrains IDEs: IntelliJ, RubyMine, PhpStorm, AppCode, PyCharm, CLion, Android Studio
+
+*.iml
+
+## Directory-based project format:
+.idea/
+# if you remove the above rule, at least ignore the following:
+
+# User-specific stuff:
+# .idea/workspace.xml
+# .idea/tasks.xml
+# .idea/dictionaries
+
+# Sensitive or high-churn files:
+# .idea/dataSources.ids
+# .idea/dataSources.xml
+# .idea/sqlDataSources.xml
+# .idea/dynamic.xml
+# .idea/uiDesigner.xml
+
+# Gradle:
+# .idea/gradle.xml
+# .idea/libraries
+
+# Mongo Explorer plugin:
+# .idea/mongoSettings.xml
+
+## File-based project format:
+*.ipr
+*.iws
+
+## Plugin-specific files:
+
+# IntelliJ
+/out/
+
+# mpeltonen/sbt-idea plugin
+.idea_modules/
+
+# JIRA plugin
+atlassian-ide-plugin.xml
+
+# Crashlytics plugin (for Android Studio and IntelliJ)
+com_crashlytics_export_strings.xml
+crashlytics.properties
+crashlytics-build.properties
+
+
+### Eclipse ###
+*.pydevproject
+.metadata
+.gradle
+bin/
+tmp/
+*.tmp
+*.bak
+*.swp
+*~.nib
+local.properties
+.settings/
+.loadpath
+
+# Eclipse Core
+.project
+
+# External tool builders
+.externalToolBuilders/
+
+# Locally stored "Eclipse launch configurations"
+*.launch
+
+# CDT-specific
+.cproject
+
+# JDT-specific (Eclipse Java Development Tools)
+.classpath
+
+# Java annotation processor (APT)
+.factorypath
+
+# PDT-specific
+.buildpath
+
+# sbteclipse plugin
+.target
+
+# TeXlipse plugin
+.texlipse
+
+
+### SublimeText ###
+# cache files for sublime text
+*.tmlanguage.cache
+*.tmPreferences.cache
+*.stTheme.cache
+
+# workspace files are user-specific
+*.sublime-workspace
+
+# project files should be checked into the repository, unless a significant
+# proportion of contributors will probably not be using SublimeText
+# *.sublime-project
+
+# sftp configuration file
+sftp-config.json
+
+# Vagrant
+.vagrant/
+ubuntu-xenial-16.04-cloudimg-console.log

README.md

@@ -1,61 +1,88 @@
 # Clojure Koans
 
-The Clojure Koans are a fun and easy way to get started with Clojure - no
-experience assumed or required.  Just follow the instructions below to start
-making tests pass!
+The Clojure Koans are a fun way to get started with Clojure - no experience
+assumed or required. Follow the instructions below to start making tests pass!
 
 
-### Getting Started
+## Getting Started
 
-The easiest and fastest way to get the koans up and running is to [download the
-latest zip file from Github](https://github.com/functional-koans/clojure-koans/downloads).
-This way, you'll have all the dependencies you need, including Clojure itself
-and JLine, and you can skip the rest of this section (skip to "Running the
-Koans").
+I recommend starting from a cloned or forked repo. This way you'll be able to
+track your progress in Git. You might want to create your own branch - that way
+if you pull back the latest koans from master, it'll be a bit easier to manage
+the inevitable conflicts if we make changes to exercises you've already
+completed.
 
-If you're starting from a cloned or forked repo, that's cool too. This way
-you'll be able to track your progress in Git, and see how your answers compare
-to others, by checking out the project's Network tab. You might want to create
-your own branch - that way if you pull back the latest koans from master, it'll
-be a bit easier to manage the inevitable conflicts if we make changes to
-exercises you've already completed.
+You have a few options for installation:
+
+- Install the dependencies for the koans (such as Clojure) on your machine
+- Use Vagrant and the configuration in this repository
+- Use Docker
+
+Instructions for each option are below!
+
+
+### Installation on Your Machine
 
 The only things you'll need to run the Clojure Koans are:
 
-- JRE 1.5 or higher
-- [clojure-1.5.1.jar](http://repo1.maven.org/maven2/org/clojure/clojure/1.5.1/clojure-1.5.1.zip)
+- JDK (I suggest version 8, but anything 6 or above should work fine)
+- [Leiningen](http://github.com/technomancy/leiningen), a build tool for Clojure
 
-You can use [Leiningen](http://github.com/technomancy/leiningen) to
-automatically install the Clojure jar in the right place. Leiningen will also
-get you a couple more jarfiles, including JLine, which allows you some of the
-functionality of readline (command-line history, for example).
+Once you've cloned this repo and installed the dependencies, you can run:
 
-### Installing dependencies
+```
+lein repl
+```
 
-Dependencies are installed automatically with lein 2, but if for some reason
-you're on lein 1 and can't upgrade, you'll need to run
+to make sure all the dependencies get downloaded properly (and then `(exit)`
+when you want to quit). See below for details on the REPL.
 
-`lein deps`
 
-which will download all dependencies you need to run the Clojure koans.
+### Installation with Vagrant
 
-I strongly recommend that you upgrade to lein 2 instead!
+Make sure you have [Vagrant](https://www.vagrantup.com/) and
+[VirtualBox](https://www.virtualbox.org) installed.
+In the root directory of the project, execute:
 
-### Running the Koans
+```
+vagrant up
+vagrant ssh
+cd /vagrant
+lein koan run
+```
 
-If you're running from the zipfile, simply run
 
-`script/run` on Mac/\*nix
+### Installation with Docker
 
-`script\run` on Windows
+Once you've got [Docker](https://www.docker.com/) installed, you're basically
+all set. You can run these commands to get started:
 
-If you're running from a checkout using lein 2, run the koans via
+To run koans:
+
+```
+docker run --rm -it -v $(pwd):/app -w /app clojure lein koan run
+```
+
+To start up a REPL:
+
+```
+docker run --rm -it -v $(pwd):/app -w /app clojure lein repl
+```
+
+
+## Running the Koans
+
+Run the koans via:
 
 `lein koan run`
 
-It's an auto-runner, so as you save your files with the correct answers, it will
-advance you to the next koan or file (conveniently, all files are prefixed with
-the sequence that you should follow).
+If want to run directly from a REPL, once you are inside the `lein repl` prompt you can run the koans with
+
+`(exec "run")`
+
+Either way, it's an auto-runner, so as you save your files with the correct
+answers, it will advance you to the next koan or file (conveniently, all files
+are prefixed with the sequence that you should follow).
 
 You'll see something like this:
 
@@ -66,7 +93,7 @@ You'll see something like this:
     (= __ true)
 
 The output is telling you that you have a failing test in the file named
-`01_equalities.clj`, on line 3. So you just need to open that file up and make
+`01_equalities.clj`, on line 3. So you need to open that file up and make
 it pass!  You'll always be filling in the blanks to make tests pass.
 Sometimes there could be several correct answers (or even an infinite number):
 any of them will work in these cases. Some tests will pass even if you replace
@@ -75,24 +102,24 @@ you give one correct expression to replace each blank.
 
 The koans differ from normal TDD in that the tests are already written for you,
 so you'll have to pay close attention to the failure messages, because up until
-the very end, making a test pass just means that the next failure message comes
+the very end, making a test pass means that the next failure message comes
 up.
 
-While it might be easy (especially at first) to just fill in the blanks making
+While it might be easy (especially at first) to fill in the blanks making
 things pass, you should work thoughtfully, making sure you understand why the
 answer is what it is.  Enjoy your path to Clojure enlightenment!
 
 
-### Trying more things out
+## Trying more things out
 
-There's a REPL (Read-Evaluate-Print Loop) included in the Clojure Koans. Just
-run:
+It's very useful to try things out in a REPL (Read-Evaluate-Print Loop)
+whenever you get stuck or curious. Run:
 
-`script/repl` on Mac/\*nix
+```
+lein repl
+```
 
-`script\repl` on Windows
-
-If you're on lein 2, `lein repl` is what you want instead.
+and you'll be able to type expressions in, and see what output they produce.
 
 Here are some interesting commands you might try, once you're in a running REPL:
 
@@ -111,10 +138,10 @@ And if those still don't make sense:
 
 will show you what those commands mean.
 
-You can exit the REPL with `CTRL-d` on any OS.
+You can exit the REPL with `CTRL-d`, `(exit)`, or `(quit)`.
 
 
-### Contributing
+## Contributing
 
 Patches are encouraged!  Make sure the answer sheet still passes
 (`lein koan test`), and send a pull request.
@@ -125,32 +152,32 @@ to add to existing koans.  So write some fun exercises, add your answers to
 
 Please follow the guidelines in
 http://tbaggery.com/2008/04/19/a-note-about-git-commit-messages.html for
-commmit messages, and put your code in a feature branch (not master) before
+commit messages, and put your code in a feature branch (not master) before
 making the pull request. This makes patches easier to review.
 
 Feel free to contact me (Colin Jones / trptcolin) on Github or elsewhere if you
 have any questions or want more direction before you start pitching in.
 
 
-### Contributors
+## Contributors
 
 https://github.com/functional-koans/clojure-koans/contributors
 
 
-### Credits
+## Credits
 
 These exercises were started by [Aaron Bedra](http://github.com/abedra) of
 [Relevance, Inc.](http://github.com/relevance) in early 2010, as a learning
 tool for newcomers to functional programming. Aaron's macro-fu makes these
-koans extremely simple and fun to use, and to improve upon, and without
-Relevance's initiative, this project would not exist.
+koans clear and fun to use and improve upon, and without Relevance's
+initiative, this project would not exist.
 
 Using the [koans](http://en.wikipedia.org/wiki/koan) metaphor as a tool for
 learning a programming language started with the
 [Ruby Koans](http://rubykoans.com) by [EdgeCase](http://github.com/edgecase).
 
 
-### License
+## License
 
 The use and distribution terms for this software are covered by the
 Eclipse Public License 1.0 (http://opensource.org/licenses/eclipse-1.0.php)

Vagrantfile

@@ -0,0 +1,31 @@
+Vagrant.configure("2") do |config|
+  config.vm.box = "ubuntu/xenial64"
+
+  config.vm.network "private_network", ip: "192.168.33.33"
+
+  config.vm.provider "virtualbox" do |vb|
+    vb.memory = "1024"
+  end
+
+  config.vm.provision "shell", inline: <<-SHELL
+    set -x
+
+    #apt-get update
+    #apt-get upgrade -y
+    apt-get install -y openjdk-8-jdk
+  SHELL
+
+  config.vm.provision "shell", privileged: false, inline: <<-SHELL
+      pwd
+      mkdir bin
+      echo "PATH=\$PATH:~/bin" >> .bashrc
+
+      cd bin
+      wget https://raw.githubusercontent.com/technomancy/leiningen/stable/bin/lein
+      chmod +x lein
+      ./lein
+
+      cd /vagrant
+      ~/bin/lein deps
+    SHELL
+end

ideaboard.txt

@@ -1,16 +1,16 @@
 Concepts / Language Features
 =====
 
-Quoting
-
 new record syntax
 Agents
 Vars
 state identity lifetime
-Metadata
 immutability / side effects
 type hints
 Pre and Post conditions of functions
+ex-info/ex-data
+reducers (?)
+transducers (?) - maybe just some basic ones, nothing too crazy
 
 Particular Functions
 =====
@@ -27,4 +27,3 @@ map-indexed
 partition-all
 partition-by
 repeatedly
-

project.clj

@@ -1,10 +1,10 @@
-(defproject clojure-koans "0.5.0"
+(defproject clojure-koans "0.5.2-SNAPSHOT"
   :description "The Clojure koans."
-  :dependencies [[org.clojure/clojure "1.5.1"]
-                 [koan-engine "0.2.3"]]
-  :dev-dependencies [[lein-koan "0.1.3"]]
-  :profiles {:dev {:dependencies [[lein-koan "0.1.3"]]}}
+  :dependencies [[org.clojure/clojure "1.10.0"]
+                 [koan-engine "0.2.5"]]
+  :dev-dependencies [[lein-koan "0.1.5"]]
+  :profiles {:dev {:dependencies [[lein-koan "0.1.5"]]}}
   :repl-options {:init-ns koan-engine.runner
-                 :init (do (use '[koan-engine.core]))}
-  :plugins [[lein-koan "0.1.3"]]
+                 :init ^:displace (do (use '[koan-engine.core]))}
+  :plugins [[lein-koan "0.1.5"]]
   :main koan-engine.runner/exec)

resources/koans.clj

@@ -6,11 +6,36 @@
                       true
                       true
                       false
-                      "foo"
-                      "foo"
+                      "hello"
+                      "hello"
+                      nil
                       3]}]
 
- ["02_lists" {"__" [1 2 3 4 5
+ ["02_strings" {"__" ["hello"
+                "world"
+                "Cool "
+                "right?"
+                0
+                11
+                false
+                6 11
+                "123"
+                ", "
+                "1" "2" "3"
+                "olleh"
+                "hello"
+                13
+                nil
+                "hello world"
+                true
+                false
+                false
+                "a"
+                true
+                true
+                false]}]
+
+ ["03_lists" {"__" [1 2 3 4 5
                  1
                  [2 3 4 5]
                  3
@@ -23,7 +48,7 @@
                  "No dice!"
                  ()]}]
 
- ["03_vectors" {"__" [1
+ ["04_vectors" {"__" [1
                    [1]
                    [nil nil]
                    2
@@ -34,50 +59,53 @@
                    [:butter :and]
                    3]}]
 
- ["04_sets" {"__" [[3]
+ ["05_sets" {"__" [[3]
                 3
                 #{1 2 3 4 5}
                 #{1 2 3 4 5}
                 #{2 3}
                 #{1 4}]}]
 
- ["05_maps" {"__" [:b 2
+ ["06_maps" {"__" [:b 2
                 1
                 2
                 2
                 1
                 1
-                "Vancouver"
+                "Sochi"
                 nil
                 :key-not-found
                 true
                 false
                 "February"
                 1 "January"
-                2006 2010 2014
-                "Sochi" "Torino" "Vancouver"]}]
+                :c 3
+                2
+                2010 2014 2018
+                "PyeongChang" "Sochi" "Vancouver"
+                2 3]}]
 
- ["06_functions" {"__" [81
+ ["07_functions" {"__" [81
                      20
                      10
                      60
                      15
-                     30]
+                     "AACC"]
                "___" [+
                       *
                       (fn [f] (f 5))
                       (fn [f] (f 5))]}]
 
- ["07_conditionals" {"__" [:a
+ ["08_conditionals" {"__" [:a
                         []
                         nil
                         :glory
                         4 6 :your-road
                         1
-                        :cocked-pistol
-                        :say-what?]}]
+                        :bicycling
+                        "is that even exercise?"]}]
 
- ["08_higher_order_functions" {"__" [4 8 12
+ ["09_higher_order_functions" {"__" [4 8 12
                                   (* x x)
                                   [false false true false false]
                                   ()
@@ -88,29 +116,29 @@
                                   100
                                   (count a) (count b)]}]
 
- ["09_runtime_polymorphism" {"__" [(str (:name a) " eats veggies.")
+ ["10_runtime_polymorphism" {"__" [(str (:name a) " eats veggies.")
                                 (str (:name a) " eats animals.")
                                 (str "I don't know what " (:name a) " eats.")
                                 "Hello World!"
                                 "Hello, you silly world."
                                 "Hello to this group: Peter, Paul, Mary!" ]}]
 
- ["10_lazy_sequences" {"__" [[1 2 3 4]
+ ["11_lazy_sequences" {"__" [[1 2 3 4]
                           [0 1 2 3 4]
                           10
                           95
-                          (range 20)
+                          [1 2 4 8 16 32 64 128]
                           :a]
                     "___" [(fn [x] x)]}]
 
- ["11_sequence_comprehensions" {"__" [[0 1 2 3 4 5]
+ ["12_sequence_comprehensions" {"__" [[0 1 2 3 4 5]
                                    (* x x)
                                    (range 10)
                                    (odd? x) (* x x)
                                    [row column]
                                    ]}]
 
- ["12_creating_functions" {"__" [true false true
+ ["13_creating_functions" {"__" [true false true
                               4
                               :a :b :c :d
                               :c :d
@@ -120,7 +148,7 @@
                                multiply-by-5
                                (comp dec square)]}]
 
- ["13_recursion" {"__" [true
+ ["14_recursion" {"__" [true
                      acc
                      (loop [coll coll
                             acc ()]
@@ -134,10 +162,10 @@
                          (recur (dec n) (* acc n))))]
                "___" [not]}]
 
- ["14_destructuring" {"__" [":bar:foo"
-                         (format (str "First comes %s, "
-                                      "then comes %s, "
-                                      "then comes %s with the baby carriage")
+ ["15_destructuring" {"__" [":bar:foo"
+                         (format (str "An Oxford comma list of %s, "
+                                      "%s, "
+                                      "and %s.")
                                  a b c)
                          (apply str
                                 (interpose " "
@@ -156,7 +184,7 @@
                                  street-address ", " city ", " state))
                           ]}]
 
- ["15_refs" {"__" ["hello"
+ ["16_refs" {"__" ["hello"
                 "hello"
                 "better"
                 "better!!!"
@@ -165,7 +193,7 @@
                 ]
           "___" [(fn [x] (+ 20 x))]}]
 
- ["16_atoms" {"__" [0
+ ["17_atoms" {"__" [0
                  1
                  (swap! atomic-clock (partial + 4))
                  20
@@ -173,17 +201,15 @@
                  atomic-clock 20 :fin
                  ]}]
 
- ["17_macros" {"__" [~(first form)
-                  ~(nth form 2)
-                  form
-                  (drop 2 form)
-                  "Hello, Macros!"
-                  10
-                  '(+ 9 1)
-                  '(* 10 2)
-                  '(+ 10 (2 * 3))]}]
+ ["18_quote" {"__" ['(1 2 3 4 5)
+                    (1 2 3 4 5)
+                    'age
+                    quote
+                    '(+ 2 3)
+                    1 2 3
+                    1 5]}]
 
- ["18_datatypes" {"__" [(print
+ ["19_datatypes" {"__" [(print
                       (str "You're really the "
                            (.category this)
                            ", " recipient "... sorry."))
@@ -195,28 +221,68 @@
                      (str "Congratulations on your Best Picture Oscar, "
                           "Evil Alien Conquerors!")]}]
 
- ["19_java_interop" {"__" [java.lang.String
+ ["20_java_interop" {"__" [java.lang.String
                         "SELECT * FROM"
                         10
                         1024
                         ]
                   "___" [#(.toUpperCase %)
-                         ]
-                  }]
- ["20_partition" {"__" [partition
+                         ]}]
+
+ ["21_partition" {"__" [partition
                         [:a :b :c]
                         '((0 1 2) (3 4))
                         5
                         :hello
                         (6 :these :are)
                         ]}]
- ["21_group_by" {"__" [odd?
+
+ ["22_group_by" {"__" [odd?
                        {5 ["hello" "world"] 3 ["foo" "bar"]}
                        {1 [{:name "Bob" :id 1}
                            {:last-name "Smith" :id 1}]
-                        2 [{:name "Mike" :id 2}]}
+                        2 [{:name "Jennifer" :id 2}]}
                        nil
                        {:naughty-list [{:name "Jimmy" :bad true}
                                        {:name "Joe" :bad true}]
-                        :nice-list [{:name "Jack" :bad false}]}]}]
+                        :nice-list [{:name "Jane" :bad false}]}]}]
+
+ ["23_meta" {"__" [{:league "National League"}
+                   {:division "West"}
+                   "This doesn't implement the IObj interface"
+                   {:foo :bar}
+                   nil
+                   \C
+                   inc
+                   :park "Oracle Park"
+                   'Giants
+                   "Giants"]}]
+
+ ["24_macros" {"__" [~(first form)
+                     ~(nth form 2)
+                     form
+                     (drop 2 form)
+                     "Hello, Macros!"
+                     10
+                     '(+ 9 1)]}]
+
+ ["25_threading_macros" {"__" [{:a 1}
+                               "Hello world, and moon, and stars"
+                               "String with a trailing space"
+                               6
+                               1
+                               [2 3 4]
+                               12
+                               [1 2 3]]}]
+
+ ["26_transducers" {"__" ['(2 3 4)
+                          [2 4]
+                          [2 4]
+                          [2 4]
+                          6]}]
+
+ ["27_multimethods" {"__" ["Hello, World!"
+                           "Hello there"
+                           1
+                           6]}]
 ]

src/koans/01_equalities.clj

@@ -24,13 +24,16 @@
   (= __ (not (= 1 nil)))
 
   "Strings, and keywords, and symbols: oh my!"
-  (= __ (= "foo" :foo 'foo))
+  (= __ (= "hello" :hello 'hello))
 
   "Make a keyword with your keyboard"
-  (= :foo (keyword __))
+  (= :hello (keyword __))
 
   "Symbolism is all around us"
-  (= 'foo (symbol __))
+  (= 'hello (symbol __))
+
+  "What could be equivalent to nothing?"
+  (= __ nil)
 
   "When things cannot be equal, they must be different"
   (not= :fill-in-the-blank __))

src/koans/02_strings.clj

@@ -0,0 +1,70 @@
+(ns koans.02-strings
+  (:require [koan-engine.core :refer :all]
+            [clojure.string :as string]))
+
+(meditations
+  "A string is nothing more than text surrounded by double quotes"
+  (= __ "hello")
+
+  "But double quotes are just magic on top of something deeper"
+  (= __ (str 'world))
+
+  "You can do more than create strings, you can put them together"
+  (= "Cool right?" (str __ __))
+
+  "You can even get certain characters"
+  (= \C (get "Characters" __))
+
+  "Or even count the characters"
+  (= __ (count "Hello World"))
+
+  "But strings and characters are not the same"
+  (= __ (= \c "c"))
+
+  "What if you only wanted to get part of a string?"
+  (= "World" (subs "Hello World" __ __))
+
+  "How about joining together elements in a list?"
+  (= __ (string/join '(1 2 3)))
+
+  "What if you wanted to separate them out?"
+  (= "1, 2, 3" (string/join __ '(1 2 3)))
+
+  "Maybe you want to separate out all your lines"
+  (= [__ __ __] (string/split-lines "1\n2\n3"))
+
+  "You may want to make sure your words are backwards"
+  (= __ (string/reverse "hello"))
+
+  "Maybe you want to find the index of the first occurrence of a substring"
+  (= 0 (string/index-of "hello world" __))
+
+  "Or maybe the last index of the same substring"
+  (= __ (string/last-index-of "hello world, hello" "hello"))
+
+  "But when something doesn't exist, nothing is found"
+  (= __ (string/index-of "hello world" "bob"))
+
+  "Sometimes you don't want whitespace cluttering the front and back"
+  (= __ (string/trim "  \nhello world \t \n"))
+
+  "You can check if something is a char"
+  (= __ (char? \c))
+
+  "But it may not be"
+  (= __ (char? "a"))
+
+  "But chars aren't strings"
+  (= __ (string? \b))
+
+  "Strings are strings"
+  (= true (string? __))
+
+  "Some strings may be blank"
+  (= __ (string/blank? ""))
+
+  "Even if at first glance they aren't"
+  (= __ (string/blank? " \n \t  "))
+
+  "However, most strings aren't blank"
+  (= __ (string/blank? "hello?\nare you out there?")))

src/koans/03_lists.clj

@@ -1,4 +1,4 @@
-(ns koans.02-lists
+(ns koans.03-lists
   (:require [koan-engine.core :refer :all]))
 
 (meditations
@@ -43,4 +43,3 @@
           (rest '())
           (catch IllegalStateException e
             "No dice!"))))
-

src/koans/04_vectors.clj

@@ -1,4 +1,4 @@
-(ns koans.03-vectors
+(ns koans.04-vectors
   (:require [koan-engine.core :refer :all]))
 
 (meditations

src/koans/05_sets.clj

@@ -1,5 +1,6 @@
-(ns koans.04-sets
-  (:require [koan-engine.core :refer :all]))
+(ns koans.05-sets
+  (:require [koan-engine.core :refer :all]
+            [clojure.set :as set]))
 
 (meditations
   "You can create a set by converting another collection"
@@ -11,11 +12,11 @@
   "Remember that a set is a *mathematical* set"
   (= __ (set '(1 1 2 2 3 3 4 4 5 5)))
 
-  "You can ask clojure for the union of two sets"
-  (= __ (clojure.set/union #{1 2 3 4} #{2 3 5}))
+  "You can ask Clojure for the union of two sets"
+  (= __ (set/union #{1 2 3 4} #{2 3 5}))
 
   "And also the intersection"
-  (= __ (clojure.set/intersection #{1 2 3 4} #{2 3 5}))
+  (= __ (set/intersection #{1 2 3 4} #{2 3 5}))
 
   "But don't forget about the difference"
-  (= __ (clojure.set/difference #{1 2 3 4 5} #{2 3 5})))
+  (= __ (set/difference #{1 2 3 4 5} #{2 3 5})))

src/koans/06_maps.clj

@@ -1,4 +1,4 @@
-(ns koans.05-maps
+(ns koans.06-maps
   (:require [koan-engine.core :refer :all]))
 
 (meditations
@@ -21,7 +21,7 @@
   (= __ (:a {:a 1 :b 2}))
 
   "But map keys need not be keywords"
-  (= __ ({2006 "Torino" 2010 "Vancouver" 2014 "Sochi"} 2010))
+  (= __ ({2010 "Vancouver" 2014 "Sochi" 2018 "PyeongChang"} 2014))
 
   "You may not be able to find an entry for a key"
   (= __ (get {:a 1 :b 2} :c))
@@ -41,10 +41,23 @@
   "You can also create a new version with an entry removed"
   (= {__ __} (dissoc {1 "January" 2 "February"} 2))
 
+  "Create a new map by merging"
+  (= {:a 1 :b 2 __ __} (merge {:a 1 :b 2} {:c 3}))
+
+  "Specify how to handle entries with same keys when merging"
+  (= {:a 1 :b __ :c 3} (merge-with + {:a 1 :b 1} {:b 1 :c 3}))
+
   "Often you will need to get the keys, but the order is undependable"
   (= (list __ __ __)
-     (sort (keys {2010 "Vancouver" 2014 "Sochi" 2006 "Torino"})))
+     (sort (keys { 2014 "Sochi" 2018 "PyeongChang" 2010 "Vancouver"})))
 
   "You can get the values in a similar way"
   (= (list __ __ __)
-     (sort (vals {2006 "Torino" 2010 "Vancouver" 2014 "Sochi"}))))
+     (sort (vals {2010 "Vancouver" 2014 "Sochi" 2018 "PyeongChang"})))
+
+  "You can even iterate over the map entries as a seq"
+  (= {:a __ :b __}
+     (into {}
+           (map
+            (fn [[k v]] [k (inc v)])
+            {:a 1 :b 2}))))

src/koans/07_functions.clj

@@ -1,4 +1,4 @@
-(ns koans.06-functions
+(ns koans.07-functions
   (:require [koan-engine.core :refer :all]))
 
 (defn multiply-by-ten [n]
@@ -23,7 +23,7 @@
   (= __ (#(+ %1 %2 %3) 4 5 6))
 
   "Arguments can also be skipped"
-  (= __ (#(* 15 %2) 1 2))
+  (= __ (#(str "AA" %2) "bb" "CC"))
 
   "One function can beget another"
   (= 9 (((fn [] ___)) 4 5))

src/koans/08_conditionals.clj

@@ -1,14 +1,12 @@
-(ns koans.07-conditionals
+(ns koans.08-conditionals
   (:require [koan-engine.core :refer :all]))
 
-(defn explain-defcon-level [exercise-term]
+(defn explain-exercise-velocity [exercise-term]
   (case exercise-term
-        :fade-out          :you-and-what-army
-        :double-take       :call-me-when-its-important
-        :round-house       :o-rly
-        :fast-pace         :thats-pretty-bad
-        :cocked-pistol     :sirens
-        :say-what?))
+        :bicycling        "pretty fast"
+        :jogging          "not super fast"
+        :walking          "not fast at all"
+        "is that even exercise?"))
 
 (meditations
   "You will face many decisions"
@@ -40,10 +38,10 @@
           'doom
           'more-doom))
 
-  "In case of emergency, sound the alarms"
-  (= :sirens
-     (explain-defcon-level __))
+  "In case of emergency, go fast"
+  (= "pretty fast"
+     (explain-exercise-velocity __))
 
   "But admit it when you don't know what to do"
   (= __
-     (explain-defcon-level :yo-mama)))
+     (explain-exercise-velocity :watching-tv)))

src/koans/09_higher_order_functions.clj

@@ -1,4 +1,4 @@
-(ns koans.08-higher-order-functions
+(ns koans.09-higher-order-functions
   (:require [koan-engine.core :refer :all]))
 
 (meditations

src/koans/10_runtime_polymorphism.clj

@@ -1,4 +1,4 @@
-(ns koans.09-runtime-polymorphism
+(ns koans.10-runtime-polymorphism
   (:require [koan-engine.core :refer :all]))
 
 (defn hello
@@ -6,7 +6,7 @@
   ([a] (str "Hello, you silly " a "."))
   ([a & more] (str "Hello to this group: "
                    (apply str
-                          (interpose ", " (concat (list a) more)))
+                          (interpose ", " (cons a more)))
                    "!")))
 
 (defmulti diet (fn [x] (:eater x)))
@@ -31,7 +31,7 @@
 
   "Animals have different names"
   (= "Thumper eats veggies."
-    (diet {:species "rabbit" :name "Thumper" :age 1 :eater :herbivore}))
+     (diet {:species "rabbit" :name "Thumper" :age 1 :eater :herbivore}))
 
   "Different methods are used depending on the dispatch function result"
   (= "Simba eats animals."

src/koans/11_lazy_sequences.clj

@@ -1,4 +1,4 @@
-(ns koans.10-lazy-sequences
+(ns koans.11-lazy-sequences
   (:require [koan-engine.core :refer :all]))
 
 (meditations
@@ -17,12 +17,12 @@
      (drop __ (range 100)))
 
   "Iteration provides an infinite lazy sequence"
-  (= __ (take 20 (iterate inc 0)))
+  (= __ (take 8 (iterate (fn [x] (* x 2)) 1)))
 
   "Repetition is key"
-  (= [:a :a :a :a :a :a :a :a :a :a ]
+  (= [:a :a :a :a :a :a :a :a :a :a]
      (repeat 10 __))
 
   "Iteration can be used for repetition"
-  (= (repeat 100 :foo)
-     (take 100 (iterate ___ :foo))))
+  (= (repeat 100 "hello")
+     (take 100 (iterate ___ "hello"))))

src/koans/12_sequence_comprehensions.clj

@@ -1,4 +1,4 @@
-(ns koans.11-sequence-comprehensions
+(ns koans.12-sequence-comprehensions
   (:require [koan-engine.core :refer :all]))
 
 (meditations
@@ -20,7 +20,7 @@
      (for [x __ :when (odd? x)]
        x))
 
-  "Combinations of these transformations is trivial"
+  "Combinations of these transformations are trivial"
   (= '(1 9 25 49 81)
      (map (fn [x] (* x x))
           (filter odd? (range 10)))

src/koans/13_creating_functions.clj

@@ -1,4 +1,4 @@
-(ns koans.12-creating-functions
+(ns koans.13-creating-functions
   (:require [koan-engine.core :refer :all]))
 
 (defn square [x] (* x x))

src/koans/14_recursion.clj

@@ -1,4 +1,4 @@
-(ns koans.13-recursion
+(ns koans.14-recursion
   (:require [koan-engine.core :refer :all]))
 
 (defn is-even? [n]
@@ -33,12 +33,12 @@
   (= '(1) (recursive-reverse [1]))
 
   "Yet it becomes more difficult the more steps you take"
-  (= '(5 4 3 2 1) (recursive-reverse [1 2 3 4 5]))
+  (= '(6 5 4 3 2) (recursive-reverse [2 3 4 5 6]))
 
-  "Simple things may appear simple."
+  "Simple things may appear simple"
   (= 1 (factorial 1))
 
-  "They may require other simple steps."
+  "They may require other simple steps"
   (= 2 (factorial 2))
 
   "Sometimes a slightly bigger step is necessary"

src/koans/15_destructuring.clj

@@ -1,4 +1,4 @@
-(ns koans.14-destructuring
+(ns koans.15-destructuring
   (:require [koan-engine.core :refer :all]))
 
 (def test-address
@@ -12,16 +12,16 @@
          [:foo :bar]))
 
   "Whether in function definitions"
-  (= (str "First comes love, "
-          "then comes marriage, "
-          "then comes Clojure with the baby carriage")
+  (= (str "An Oxford comma list of apples, "
+          "oranges, "
+          "and pears.")
      ((fn [[a b c]] __)
-      ["love" "marriage" "Clojure"]))
+      ["apples" "oranges" "pears"]))
 
   "Or in let expressions"
-  (= "Rich Hickey aka The Clojurer aka Go Time aka Macro Killah"
+  (= "Rich Hickey aka The Clojurer aka Go Time aka Lambda Guru"
      (let [[first-name last-name & aliases]
-           (list "Rich" "Hickey" "The Clojurer" "Go Time" "Macro Killah")]
+           (list "Rich" "Hickey" "The Clojurer" "Go Time" "Lambda Guru")]
        __))
 
   "You can regain the full argument if you like arguing"
@@ -29,7 +29,7 @@
      (let [[first-name last-name :as full-name] ["Stephen" "Hawking"]]
        __))
 
-  "Break up maps by key"
+  "Break up maps by keys"
   (= "123 Test Lane, Testerville, TX"
      (let [{street-address :street-address, city :city, state :state} test-address]
        __))

src/koans/16_refs.clj

@@ -1,4 +1,4 @@
-(ns koans.15-refs
+(ns koans.16-refs
   (:require [koan-engine.core :refer :all]))
 
 (def the-world (ref "hello"))

src/koans/17_atoms.clj

@@ -1,4 +1,4 @@
-(ns koans.16-atoms
+(ns koans.17-atoms
   (:require [koan-engine.core :refer :all]))
 
 (def atomic-clock (atom 0))

src/koans/18_quote.clj

@@ -0,0 +1,25 @@
+(ns koans.18-quote
+  (:require [koan-engine.core :refer :all]))
+
+
+(meditations
+  "Wrap a quote around a list to suppress evaluation"
+  (= (quote (1 2 3 4 5)) __)
+
+  "There is a shortcut too!"
+  (= (quote __) '(1 2 3 4 5))
+
+  "You can quote symbols as well as lists... without evaluation!"
+  (= __ (let [age 9] (quote age)))
+
+  "You can use a literal list as a data collection without having Clojure try to call a function"
+  (= (cons 1 (__ (2 3))) (list 1 2 3) (cons 1 [2 3]))
+
+  "The quote affects all of its arguments, not just the top level"
+  (= (list 1 __) '(1 (+ 2 3)))
+
+  "Syntax-quote (`) acts similarly to the normal quote"
+  (= (list __ __ __) `(1 2 3) '(1 2 3))
+
+  "Unquote (~) within a syntax-quoted expression lets you mark specific expressions as requiring evaluation"
+  (= (list __ __) `(1 ~(+ 2 3)) '(1 5)))

src/koans/19_datatypes.clj

@@ -1,4 +1,4 @@
-(ns koans.18-datatypes
+(ns koans.19-datatypes
   (:require [koan-engine.core :refer :all]))
 
 (defrecord Nobel [prize])

src/koans/20_java_interop.clj

@@ -1,4 +1,4 @@
-(ns koans.19-java-interop
+(ns koans.20-java-interop
   (:require [koan-engine.core :refer :all]))
 
 (meditations

src/koans/21_partition.clj

@@ -1,4 +1,4 @@
-(ns koans.20-partition
+(ns koans.21-partition
   (:require [koan-engine.core :refer :all]))
 
 (meditations
@@ -8,14 +8,14 @@
   "But watch out if there are not enough elements to form n sequences"
   (= '(__) (partition 3 [:a :b :c :d :e]))
 
-  "You can use partition-all to also get partitions with less than n elements"
+  "You can use partition-all to include any leftovers too"
   (= __ (partition-all 3 (range 5)))
 
   "If you need to, you can start each sequence with an offset"
   (= '((0 1 2) (5 6 7) (10 11 12)) (partition 3 __ (range 13)))
 
-  "Consider padding the last sequence with some default values..."
+  "Consider padding the last sequence with some default values"
   (= '((0 1 2) (3 4 5) (6 :hello)) (partition 3 3 [__] (range 7)))
 
-  "... but notice that they will only pad up to the given sequence length"
+  "But notice that they will only pad up to the given sequence length"
   (= '((0 1 2) (3 4 5) __) (partition 3 3 [:these :are "my" "words"] (range 7))))

src/koans/22_group_by.clj

@@ -1,4 +1,4 @@
-(ns koans.21-group-by
+(ns koans.22-group-by
   (:require [koan-engine.core :refer :all]))
 
 (defn get-odds-and-evens [coll]
@@ -6,11 +6,9 @@
     [odds evens]))
 
 (meditations
-
-  "To categorize a collection by some function, use group-by."
+  "To categorize a collection by some function, use group-by"
   (= __ (group-by count ["hello" "world" "foo" "bar"]))
 
-
   "You can simulate filter + remove in one pass"
   (= (get-odds-and-evens [1 2 3 4 5])
      ((juxt filter remove) odd? [1 2 3 4 5])
@@ -19,20 +17,20 @@
   "You can also group by a primary key"
   (= __
      (group-by :id [{:id 1 :name "Bob"}
-                    {:id 2 :name "Mike"}
+                    {:id 2 :name "Jennifer"}
                     {:id 1 :last-name "Smith"} ]))
 
-  "But be careful when you group by non-required key"
+  "But be careful when you group by a non-required key"
   (= {"Bob" [{:name "Bob" :id 1}]
-      "Mike" [{:name "Mike" :id 2}]
+      "Jennifer" [{:name "Jennifer" :id 2}]
       __ [{:last-name "Smith" :id 1}]}
    (group-by :name [{:id 1 :name "Bob"}
-                    {:id 2 :name "Mike"}
+                    {:id 2 :name "Jennifer"}
                     {:id 1 :last-name "Smith"}]))
 
   "The true power of group-by comes with custom functions"
   (= __
      (group-by #(if (:bad %) :naughty-list :nice-list)
                [{:name "Jimmy" :bad true}
-                {:name "Jack" :bad false}
+                {:name "Jane" :bad false}
                 {:name "Joe" :bad true}])))

src/koans/23_meta.clj

@@ -0,0 +1,51 @@
+(ns koans.23-meta
+  (:require [koan-engine.core :refer :all]))
+
+(def giants
+  (with-meta 'Giants
+    {:league "National League"}))
+
+(meditations
+  "Some objects can be tagged using the with-meta function"
+  (= __ (meta giants))
+
+  "Or more succinctly with a reader macro"
+  (= __ (meta '^{:division "West"} Giants))
+
+  "While others can't"
+  (= __ (try
+          (with-meta
+            2
+            {:prime true})
+          (catch ClassCastException e
+            "This doesn't implement the IObj interface")))
+
+  "Notice when metadata carries over"
+  (= __ (meta (merge '^{:foo :bar} {:a 1 :b 2}
+                     {:b 3 :c 4})))
+
+  "And when it doesn't"
+  (= __ (meta (merge {:a 1 :b 2}
+                     '^{:foo :bar} {:b 3 :c 4})))
+
+  "Metadata can be used as a type hint to avoid reflection during runtime"
+  (= __ (#(.charAt ^String % 0) "Cast me"))
+
+  "You can directly update an object's metadata"
+  (= 8 (let [giants
+             (with-meta
+               'Giants
+               {:world-series-titles (atom 7)})]
+         (swap! (:world-series-titles (meta giants)) __)
+         @(:world-series-titles (meta giants))))
+
+  "You can also create a new object from another object with metadata"
+  (= {:league "National League" :park "Oracle Park"}
+     (meta (vary-meta giants
+                      assoc __ __)))
+
+  "But it won't affect behavior like equality"
+  (= __ (vary-meta giants dissoc :league))
+
+  "Or the object's printed representation"
+  (= __ (pr-str (vary-meta giants dissoc :league))))

src/koans/24_macros.clj

@@ -1,4 +1,4 @@
-(ns koans.17-macros
+(ns koans.24-macros
   (:require [koan-engine.core :refer :all]))
 
 (defmacro hello [x]
@@ -7,23 +7,23 @@
 (defmacro infix [form]
   (list (second form) (first form) (nth form 2)))
 
-(defmacro infix-better [form]
+(defmacro infix-concise [form]
   `(~(second form) ; Note the syntax-quote (`) and unquote (~) characters!
     __
-    __ ))
+    __))
 
-(defmacro r-infix [form]
+(defmacro recursive-infix [form]
   (cond (not (seq? form))
         __
         (= 1 (count form))
-        `(r-infix ~(first form))
+        `(recursive-infix ~(first form))
         :else
         (let [operator (second form)
               first-arg (first form)
               others __]
           `(~operator
-            (r-infix ~first-arg)
-            (r-infix ~others)))))
+            (recursive-infix ~first-arg)
+            (recursive-infix ~others)))))
 
 (meditations
   "Macros are like functions created at compile time"
@@ -36,10 +36,10 @@
   (= __ (macroexpand '(infix (9 + 1))))
 
   "You can do better than that - hand crafting FTW!"
-  (= __ (macroexpand '(infix-better (10 * 2))))
+  (= '(* 10 2) (macroexpand '(infix-concise (10 * 2))))
 
-  "Things don't always work as you would like them to... "
-  (= __ (macroexpand '(infix-better ( 10 + (2 * 3)))))
+  "Things don't always work as you would like them to"
+  (= '(+ 10 (2 * 3)) (macroexpand '(infix-concise (10 + (2 * 3)))))
 
   "Really, you don't understand recursion until you understand recursion"
-  (= 36 (r-infix (10 + (2 * 3) + (4 * 5)))))
+  (= 36 (recursive-infix (10 + (2 * 3) + (4 * 5)))))

src/koans/25_threading_macros.clj

@@ -0,0 +1,66 @@
+(ns koans.25-threading-macros
+  (:require [koan-engine.core :refer :all]))
+
+(def a-list
+  '(1 2 3 4 5))
+
+(def a-list-with-maps
+  '({:a 1} {:a 2} {:a 3}))
+
+(defn function-that-takes-a-map [map a b]
+  (get map :a))
+
+(defn function-that-takes-a-coll [a b coll]
+  (map :a coll))
+
+(meditations
+ "We can use thread first for more readable sequential operations"
+ (= __
+    (-> {}
+        (assoc :a 1)))
+
+ "Consider also the case of strings"
+ (= __
+    (-> "Hello world"
+        (str ", and moon")
+        (str ", and stars")))
+
+ "When a function has no arguments to partially apply, just reference it"
+ (= __
+    (-> "String with a trailing space "
+        clojure.string/trim))
+
+ "Most operations that take a scalar value as an argument can be threaded-first"
+ (= __
+    (-> {}
+        (assoc :a 1)
+        (assoc :b 2)
+        (assoc :c {:d 4
+                   :e 5})
+        (update-in [:c :e] inc)
+        (get-in [:c :e])))
+
+ "We can use functions we have written ourselves that follow this pattern"
+ (= __
+    (-> {}
+        (assoc :a 1)
+        (function-that-takes-a-map "hello" "there")))
+
+ "We can also thread last using ->>"
+ (= __
+    (->> [1 2 3]
+         (map inc)))
+
+ "Most operations that take a collection can be threaded-last"
+ (= __
+    (->> a-list
+         (map inc)
+         (filter even?)
+         (into [])
+         (reduce +)))
+
+ "We can use functions we have written ourselves that follow this pattern"
+ (= __
+    (->> a-list-with-maps
+         (function-that-takes-a-coll "hello" "there")
+         (into []))))

src/koans/26_transducers.clj

@@ -0,0 +1,30 @@
+(ns koans.26-transducers
+  (:require [koan-engine.core :refer :all]))
+
+(def example-transducer
+  (map inc))
+
+(def transforms
+  (comp (map inc)
+     (filter even?)))
+
+(meditations
+ "A sequence operation with only one argument often returns a transducer"
+ (= __
+    (sequence example-transducer [1 2 3]))
+
+ "Consider that sequence operations can be composed as transducers"
+ (= __
+    (transduce transforms conj [1 2 3]))
+
+ "We can do this eagerly"
+ (= __
+    (into [] transforms [1 2 3]))
+
+ "Or lazily"
+ (= __
+    (sequence transforms [1 2 3]))
+
+ "The transduce function can combine mapping and reduction"
+ (= __
+    (transduce transforms + [1 2 3])))

src/koans/27_multimethods.clj

@@ -0,0 +1,44 @@
+(ns koans.27-multimethods
+  (:require [koan-engine.core :refer :all]))
+
+(defmulti multimethod-without-args
+ (fn [keyword-arg] keyword-arg))
+
+(defmethod multimethod-without-args :first [_]
+ (str "Hello, World!"))
+
+(defmethod multimethod-without-args :second [_]
+ (str "Hello there"))
+
+(defmulti multimethod-with-args
+ (fn [opt-one opt-two] opt-one))
+
+(defmethod multimethod-with-args :path-one [_ opts]
+ (:first-opt opts))
+
+(defmethod multimethod-with-args :path-two [_ opts]
+ (let [numbers (:second-opt opts)]
+  (->> numbers
+       (map inc)
+       (reduce +))))
+
+(defmethod multimethod-with-args :path-three [_])
+
+(meditations
+ "A multimethod takes one or more arguments to dispatch on"
+ (= __
+    (multimethod-without-args :first))
+
+ "Though it can be ignored and represented by _ in defmethods"
+ (= __
+    (multimethod-without-args :second))
+
+ "Alternatively, we can use the arguments in defmethods"
+ (= __
+    (multimethod-with-args :path-one {:first-opt 1
+                                      :second-opt 2}))
+ 
+ "This allows us to do something different in each method implementation"
+ (= __
+    (multimethod-with-args :path-two {:first-opt 1
+                                      :second-opt [0 1 2]})))