Pune Clojure Course Outline
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The document discusses Clojure, a programming language created by Rich Hickey, emphasizing its functional programming features, concurrency capabilities, and integration with Java. It highlights the language's flexibility with data structures, such as lists, vectors, and maps, as well as its dynamic development environment. The text also mentions various libraries and communities associated with Clojure, pointing to its extensive applications and resources for developers.
![ Numbers 1
3.14
22/7
Characters a
b
c
Booleans true
false
Comments ;;
Ignore
Strings “foobar”
Nothing nil
Symbols thisfn
Keywords :this
:that
RegEx Patterns #“[a-‐zA-‐
Z0-‐9]+”](https://image.slidesharecdn.com/puneclojurecourse-100705053613-phpapp02/85/Pune-Clojure-Course-Outline-7-320.jpg)
![ Lists (1
2
3)
(list
“foo”
“bar”
“baz”)
Vectors [1
2
3]
(vector
“foo”
“bar”
“baz”)
Maps {:x
1,
:y
2}
(hash-‐map
:foo
1
:bar
2)
Sets #{a
e
i
o
u}
(hash-‐set
“cat”
“dog”)](https://image.slidesharecdn.com/puneclojurecourse-100705053613-phpapp02/85/Pune-Clojure-Course-Outline-8-320.jpg)
![ Function calls (function
arguments*)
(def
hello
(fn
[]
“Hello,
world!”))
-‐>
#’user/hello
(hello)
-‐>
“Hello,
world!”
(defn
hello
([]
(hello
“world”))
([name]
(str
“Hello,
”
name
“!”)))](https://image.slidesharecdn.com/puneclojurecourse-100705053613-phpapp02/85/Pune-Clojure-Course-Outline-10-320.jpg)
![ A technique of doing structural binding in a function
arg list or let binding
(defn
list-‐xyz
[xyz-‐map]
(list
(:x
xyz-‐map)
(:y
xyz-‐map)
(:z
xyz-‐map)))
(list-‐xyz
{:x
1,
:y
2
:z
3})
-‐>
(1
2
3)](https://image.slidesharecdn.com/puneclojurecourse-100705053613-phpapp02/85/Pune-Clojure-Course-Outline-17-320.jpg)
![//
From
Apache
Commons
Lang,
http://commons.apache.org/lang/
public
static
int
indexOfAny(String
str,
char[]
searchChars)
{
if
(isEmpty(str)
||
ArrayUtils.isEmpty(searchChars))
{
return
-‐1;
}
for
(int
i
=
0;
i
<
str.length();
i++)
{
char
ch
=
str.charAt(i);
for
(int
j
=
0;
j
<
searchChars.length;
j++)
{
if
(searchChars[j]
==
ch)
{
return
i;
}
}
}
return
-‐1;
}](https://image.slidesharecdn.com/puneclojurecourse-100705053613-phpapp02/85/Pune-Clojure-Course-Outline-18-320.jpg)
![(defn
indexed
[coll]
(map
vector
(iterate
inc
0)
coll))](https://image.slidesharecdn.com/puneclojurecourse-100705053613-phpapp02/85/Pune-Clojure-Course-Outline-19-320.jpg)
![(defn
indexed
[coll]
(map
vector
(iterate
inc
0)
coll))
(defn
index-‐filter
[pred
coll]
(for
[[idx
elt]
(indexed
coll)
:when
(pred
elt)]
idx))](https://image.slidesharecdn.com/puneclojurecourse-100705053613-phpapp02/85/Pune-Clojure-Course-Outline-20-320.jpg)
![(defn
indexed
[coll]
(map
vector
(iterate
inc
0)
coll))
(defn
index-‐filter
[pred
coll]
(when
pred
(for
[[idx
elt]
(indexed
coll)
:when
(pred
elt)]
idx)))
(index-‐filter
#{a
e
i
o
o}
"The
quick
brown
fox")
-‐>
(2
6
12
17)
(index-‐filter
#(>
(.length
%)
3)
["The"
"quick"
"brown"
"fox"])
-‐>
(1
2)](https://image.slidesharecdn.com/puneclojurecourse-100705053613-phpapp02/85/Pune-Clojure-Course-Outline-21-320.jpg)
![ Encapsulation through closures
Polymorphism through multi-methods
Inheritance through duck-typing
(defmulti
interest
:type)
(defmethod
interest
:checking
[a]
0)
(defmethod
interest
:savings
[a]
0.05)
(defmulti
service-‐charge
(fn
[acct]
[(account-‐level
acct)
(:tag
acct)]))
(defmethod
service-‐charge
[::Basic
::Checking]
[_]
25)
(defmethod
service-‐charge
[::Basic
::Savings]
[_]
10)
(defmethod
service-‐charge
[::Premium
::Checking]
[_]
0)
(defmethod
service-‐charge
[::Premium
::Savings]
[_]
0)](https://image.slidesharecdn.com/puneclojurecourse-100705053613-phpapp02/85/Pune-Clojure-Course-Outline-25-320.jpg)
![ A facility to extend the compiler with user code
Used to define syntactic constructs which would
otherwise require primitives/built-in support
(try-‐or
(/
1
0)
(reduce
+
[1
2
3
4])
(partition
(range
10)
2)
(map
+
[1
2
3
4]))](https://image.slidesharecdn.com/puneclojurecourse-100705053613-phpapp02/85/Pune-Clojure-Course-Outline-26-320.jpg)
Pune Clojure Course Outline
- 3. Programming Language Nerd Co-founder & CTO, Infinitely Beta Clojure programmer since the early days Curator of Planet Clojure Author of “Clojure in Practice” (ETA Sep, 2011)
- 4. History Metadata Data Structures Java Inter-op Syntax Concurrency Functions Multi-methods Sequences Macros Namespaces Clojure Contrib
- 5. Created by Rich Hickey in 2007 Open Sourced in 2008 First large deployment in Jan, 2009 Second in Apr, same year We’ve come a long way since then!
- 6. Programming languages OO is overrated haven’t really changed much Polymorphism is good Creating large-scale, Multi-core is the future concurrent software is still hard VMs are the next-gen platforms Functional Programming rocks Ecosystem matters Lisp is super power Dynamic development
- 7. Numbers 1 3.14 22/7 Characters a b c Booleans true false Comments ;; Ignore Strings “foobar” Nothing nil Symbols thisfn Keywords :this :that RegEx Patterns #“[a-‐zA-‐ Z0-‐9]+”
- 8. Lists (1 2 3) (list “foo” “bar” “baz”) Vectors [1 2 3] (vector “foo” “bar” “baz”) Maps {:x 1, :y 2} (hash-‐map :foo 1 :bar 2) Sets #{a e i o u} (hash-‐set “cat” “dog”)
- 9. There is no other syntax! Data structures are the code No other text based syntax, only different interpretations Everything is an expression (s-exp) All data literals stand for themselves, except symbols & lists
- 10. Function calls (function arguments*) (def hello (fn [] “Hello, world!”)) -‐> #’user/hello (hello) -‐> “Hello, world!” (defn hello ([] (hello “world”)) ([name] (str “Hello, ” name “!”)))
- 11. “It is better to have 100 functions operate on one data structure than 10 functions on 10 data-structures.” Alan J. Perlis
- 12. An abstraction over traditional Lisp lists Provides an uniform way of walking through different data-structures Sample sequence functions seq first rest filter remove for partition reverse sort map reduce doseq
- 13. Analogous to Java packages, but with added dynamism A mapping of symbols to actual vars/classes Can be queried and modified dynamically Usually manipulated via the ns macro
- 14. Data about data Can annotate any symbol or collection Mainly used by developers to mark data structures with some special information Clojure itself uses it heavily (def x (with-‐meta {:x 1} {:source :provider-‐1})) -‐> #’user/x (meta x) -‐> {:source :provider-‐1}
- 15. Wrapper free interface to Java Syntactic sugar makes calling Java easy & readable Core Clojure abstractions are Java interfaces (will change) Clojure functions implement Callable & Runnable Clojure sequence lib works with Java iterables Near native speed
- 16. (ClassName. args*) (instanceMember instance args*) (ClassName/staticMethod args*) ClassName/STATIC_FIELD (.toUpperCase “clojure”) -‐> “CLOJURE” (System/getProperty “java.vm.version”) -‐> “16.3-‐b01-‐279” Math/PI -‐> 3.14… (.. System (getProperties) (get “os.name”)) -‐> “Mac OS X”
- 17. A technique of doing structural binding in a function arg list or let binding (defn list-‐xyz [xyz-‐map] (list (:x xyz-‐map) (:y xyz-‐map) (:z xyz-‐map))) (list-‐xyz {:x 1, :y 2 :z 3}) -‐> (1 2 3)
- 18. // From Apache Commons Lang, http://commons.apache.org/lang/ public static int indexOfAny(String str, char[] searchChars) { if (isEmpty(str) || ArrayUtils.isEmpty(searchChars)) { return -‐1; } for (int i = 0; i < str.length(); i++) { char ch = str.charAt(i); for (int j = 0; j < searchChars.length; j++) { if (searchChars[j] == ch) { return i; } } } return -‐1; }
- 19. (defn indexed [coll] (map vector (iterate inc 0) coll))
- 20. (defn indexed [coll] (map vector (iterate inc 0) coll)) (defn index-‐filter [pred coll] (for [[idx elt] (indexed coll) :when (pred elt)] idx))
- 21. (defn indexed [coll] (map vector (iterate inc 0) coll)) (defn index-‐filter [pred coll] (when pred (for [[idx elt] (indexed coll) :when (pred elt)] idx))) (index-‐filter #{a e i o o} "The quick brown fox") -‐> (2 6 12 17) (index-‐filter #(> (.length %) 3) ["The" "quick" "brown" "fox"]) -‐> (1 2)
- 22. for doseq if cond condp partition loop recur str map reduce filter defmacro apply comp complement defstruct drop drop-‐last drop-‐while format iterate juxt map mapcat memoize merge partial partition partition-‐all re-‐seq reductions reduce remove repeat repeatedly zipmap
- 23. Simultaneous execution Avoid reading; yielding inconsistent data Synchronous Asynchronous Coordinated ref Independent atom agent Unshared var
- 24. Generalised indirect dispatch Dispatch on an arbitrary function of the arguments Call sequence Call dispatch function on args to get dispatch value Find method associated with dispatch value Else call default method Else error
- 25. Encapsulation through closures Polymorphism through multi-methods Inheritance through duck-typing (defmulti interest :type) (defmethod interest :checking [a] 0) (defmethod interest :savings [a] 0.05) (defmulti service-‐charge (fn [acct] [(account-‐level acct) (:tag acct)])) (defmethod service-‐charge [::Basic ::Checking] [_] 25) (defmethod service-‐charge [::Basic ::Savings] [_] 10) (defmethod service-‐charge [::Premium ::Checking] [_] 0) (defmethod service-‐charge [::Premium ::Savings] [_] 0)
- 26. A facility to extend the compiler with user code Used to define syntactic constructs which would otherwise require primitives/built-in support (try-‐or (/ 1 0) (reduce + [1 2 3 4]) (partition (range 10) 2) (map + [1 2 3 4]))
- 27. clojure.contrib.http.agent clojure.contrib.io clojure.contrib.json clojure.contrib.seq-utils clojure.contrib.pprint clojure.contrib.string
- 28. Compojure Cascalog ClojureQL Enlive Incanter Congomongo Leiningen Pallet FleetDB Many more! clojure-hadoop
- 29. Clojure http://clojure.org Clojure group http://bit.ly/clojure-group IRC #clojure on irc.freenode.net Source http://github.com/clojure Wikibook http://bit.ly/clojure-wikibook