Clojure Environment

This notebook describes and creates the default Clojure environment in Nextjournal. Check out the showcase if you want to see what the environment contains. To see how it’s built, see setup.

If you don't specify a version, Clojure version

"1.10.1"
is used. However, it's easy to run Clojure version
"1.9.0"
by including it as a dependency in the runtime's deps.edn.

Showcase

Package Management

At Boot via deps.edn

Working with deps.edn is as easy as creating a Code Listing and writing a typical edn configuration map with a top-level key for :deps.

{:deps
 {org.clojure/clojure {:mvn/version "1.10.1"}
  compliment {:mvn/version "0.3.9"}}}
deps.edn
Extensible Data Notation

After mounting the Code Listing (here called deps.edn) and restarting the runtime, the dependencies will be available.

(clojure-version)
0.1s
1.10 (Clojure)
Clojure
"1.10.1"

For details on how to mount deps.edn and restart a runtime, see Clojure Dependencies.

At Runtime via tools.deps/add-lib

add-lib, part of tools.deps.alpha, dynamically adds libraries to a running REPL session.

The following deps.edn configuration map contains two of the three possible coordinate types: Maven (clojure) and git (tools.deps.alpha); local is the unused third.

{:deps
  { org.clojure/clojure {:mvn/version "1.9.0"}
    org.clojure/tools.deps.alpha {
      :git/url "https://github.com/clojure/tools.deps.alpha.git"
      :sha "d0b33e0d346736aa985c150145b332f97b92135e"}}}
deps.edn
Extensible Data Notation

Note the use of Clojure 1.9 in this example rather than the Nextjournal default of 1.10.

(clojure-version)
0.1s
1.9 (Clojure)
Clojure
"1.9.0"

Load tools.deps.alpha and then use add-lib to add core.async on the fly. Note core.async was not included in deps.edn.

(use 'clojure.tools.deps.alpha.repl)
3.4s
1.9 (Clojure)
Clojure
(add-lib 'org.clojure/core.async {:mvn/version "0.4.490"})
6.6s
1.9 (Clojure)
Clojure
true

Require core.async and test.

(require '[clojure.core.async :as async])
(async/timeout 100)
13.2s
1.9 (Clojure)
Clojure
Vector(4) [clojure.core.async.impl.channels.ManyToManyChannel, "0x692d126d", "clojure.core.async.impl.channels.ManyToManyChannel@692d126d", Map]

Plotting

Basic: Using Data From Clojure

Generate some random data for plotly and plot it by selecting the plotly viewer via the :nextjournal/viewer metadata attribute.

(defn get-coordinates [y] 
	{:x '(0 10 20 30 40) 
	 :y (take 5 (repeatedly #(rand-int y)))
   :type "scatter"
   :text ["one" "two" "three"]})
^{:nextjournal/viewer :plotly}
{:data [(conj (get-coordinates 35) {:name "The Federation"}) 
        (conj (get-coordinates 35) {:name "The Empire"})]
 :layout {:autosize false :width 600 :height 500 
          :xaxis1 {:title "year"} 
          :yaxis1 {:title "revenue"}}}
0.7s
plotly1.10 (Clojure)
Clojure

ClojureScript support is currently experimental. A list of features and caveats is available in the ClojureScript template.

Advanced: Using Data From Datomic

Datomic queries return data that is simple to work with in Clojure and ClojureScript. This section is a brief demonstration.

The following Clojure runtimes transclude a complete Datomic environment and dataset. For a deeper understanding of how to setup Datomic Free with Nextjournal, please read this Datomic article.

Setup

Start the transactor.

/usr/bin/nohup /datomic-free/bin/transactor /datomic-free/config/samples/free-transactor-template.properties &> /datomic-free.log & sleep 1
tail /datomic-free.log
1.8s
Datomic (Bash in Clojure)

Load a subset of the MusicBrainz dataset. In this case, music-related information from 1968 to 1973.

/datomic-free/bin/datomic restore-db file:/mbrainz-1968-1973 datomic:free://localhost:4334/mbrainz-1968-1973
27.6s
Datomic (Bash in Clojure)

Require Datomic and get a value of the database from the connection, defined by (d/connect uri). The d/db API returns the latest db value from the specified connection.

(require '[datomic.api :as d])
(def uri "datomic:free://localhost:4334/mbrainz-1968-1973")
(def conn (d/connect uri))
(def db (d/db conn))
7.7s
Datomic (Clojure)
user/db
Query

The query, written in Datalog. It is looking for every John Lennon album with a release date from 1968 to 1973.

(def rules
  '[;; Given ?t bound to track entity-ids, binds ?r to the corresponding
    ;; set of album release entity-ids
 [(track-release ?t ?r)
  [?m :medium/tracks ?t]
  [?r :release/media ?m]]])
(def albums-year 
  (into [] (d/q '[:find ?album ?year
 :in $ % ?artist-name
 :where
 [?a :artist/name   ?artist-name]
 [?t :track/artists ?a]
 [?t :track/name    ?title]
 (track-release ?t ?r)
 [?r :release/name  ?album]
 [?r :release/year  ?year]]
     db rules "John Lennon")))
albums-year
1.7s
Datomic (Clojure)
Vector(16) [Vector(2), Vector(2), Vector(2), Vector(2), Vector(2), Vector(2), Vector(2), Vector(2), Vector(2), Vector(2), Vector(2), Vector(2), Vector(2), Vector(2), Vector(2), Vector(2)]
Plot

First, collect albums by year. This will make them easy to count and display later.

(defn add-album-to-year [m year title]
  (if (contains? m year) 
    (assoc m year (conj (year m) title)) 
    (assoc m year [title])))
(defn albums-by-year [albums-year m]
  (if-let [album (first albums-year)]
    (let [[title year] album
           sorted-albums (add-album-to-year m (keyword (str year)) title)]
	    (albums-by-year (rest albums-year) sorted-albums))
  	  m))
(albums-by-year albums-year {})
0.2s
Datomic (Clojure)
Map {:1971: Vector(4), :1969: Vector(3), :1973: Vector(3), :1972: Vector(3), :1970: Vector(3)}

Second, provide the ploty with the :data and :layout information and plot it by setting the {:nextjournal/viewer :plotly} metadata.

(let [final-sort (albums-by-year albums-year {})]
  ^{:nextjournal/viewer :plotly}
  {:data [{:x (keys final-sort)
           :y (map #(count (second %)) (albums-by-year albums-year {}))
           :type "bar"}]
   :layout {:autosize false :width 600 :height 500
          :type "bar"
          :xaxis1 {:title "Year"} 
          :yaxis1 {:title "# of Albums"}}})
0.1s
albumsDatomic (Clojure)
Loading viewer…

Setup

Build the default Clojure environment

Install Clojure

Now for the Clojure installation. Note that the stable Clojure version is set as an environment variable on the runtime. Also set UseG1GC Java option as workaround for a GraalVM serial garbage collector bug. Remove when 19.3.1 is released. —MPD, 2019.12.04

Clojure
Clojure (Bash)
exporting environment
Type: Nextjournal
Environment:
Machine Type:
Environment Variables:
CLOJURE_VERSION1.10.1.492
_JAVA_OPTIONS-XX:+UseG1GC
Download this environment as a Docker image from:

Install the one missing dependency, rlwrap, as well as git.

apt-get -qq update
DEBIAN_FRONTEND=noninteractive apt-get install --no-install-recommends \
  rlwrap
apt-get clean
rm -rf /var/lib/apt/lists/*
11.9s
Clojure (Bash)

Next, download and run the Clojure installer.

wget --progress=bar:force -P /results \
  https://download.clojure.org/install/linux-install-${CLOJURE_VERSION}.sh 
0.8s
Clojure (Bash)
linux-install-1.10.1.492.sh
/bin/bash NJ__REF_
3.5s
Clojure (Bash)

Test clojure from the command line.

clojure -e "(clojure-version)"
13.8s
Clojure (Bash)

Add Some Tools and Dependencies

Install leiningen.

cd /usr/local/bin
wget --progress=bar:force \
  https://raw.githubusercontent.com/technomancy/leiningen/stable/bin/lein
chmod +x lein
./lein
12.3s
Clojure (Bash)

Install tools.deps.alpha to get add-lib to dynamically add libraries, and compliment for autocompletion.

clojure -Sdeps '{ :deps {
  org.clojure/tools.deps.alpha {:mvn/version "0.8.599"}
  compliment/compliment {:mvn/version "0.3.9"}
}}' -e "(clojure-version)"
26.6s
Clojure (Bash)

Install the Apache Arrow and Parquet format libraries.

clojure  -Sdeps '{ :deps {
  org.apache.arrow/arrow-format {:mvn/version "0.15.1"}
  org.apache.arrow/arrow-plasma {:mvn/version "0.15.1"}
  org.apache.parquet/parquet-format {:mvn/version "2.7.0"}
}}' -Stree
19.4s
Clojure (Bash)

Pre-install Clojure 1.9.0.

clojure  -Sdeps '{ :deps {
  org.clojure/clojure {:mvn/version "1.9.0"}
}}' -Stree
18.2s
Clojure (Bash)

Check size.

du -hsx /
1.9s
Clojure (Bash)
Runtimes (4)