Pune Clojure Course Outline

  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)

  History   Metadata

  Data Structures   Java Inter-op

  Syntax   Concurrency

  Functions   Multi-methods

  Sequences   Macros

  Namespaces   Clojure Contrib

  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!

  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

  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]+”

  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”)

  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

  Function calls (function
arguments*)

(def
hello
(fn
[]
“Hello,
world!”))

-‐>
#’user/hello

(hello)

-‐>
“Hello,
world!”

(defn
hello

([]
(hello
“world”))

([name]
(str
“Hello,
”
name
“!”)))

“It is better to have 100 functions operate on one data structure
than 10 functions on 10 data-structures.”
Alan J. Perlis

  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

  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

  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}

  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

(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”

  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)

//
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;

}

(defn
indexed
[coll]
(map
vector
(iterate
inc
0)
coll))

(defn
indexed
[coll]
(map
vector
(iterate
inc
0)
coll))

(defn
index-‐filter
[pred
coll]

(for
[[idx
elt]
(indexed
coll)
:when
(pred
elt)]

idx))

(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)

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

  Simultaneous execution

  Avoid reading; yielding inconsistent data

Synchronous Asynchronous
Coordinated ref

Independent atom
agent

Unshared var

  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

  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)

  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]))

  clojure.contrib.http.agent

  clojure.contrib.io

  clojure.contrib.json

  clojure.contrib.seq-utils

  clojure.contrib.pprint

  clojure.contrib.string

  Compojure   Cascalog

  ClojureQL   Enlive

  Incanter   Congomongo

  Leiningen   Pallet

  FleetDB   Many more!

  clojure-hadoop

  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

http://infinitelybeta.com/jobs/

Pune Clojure Course Outline

More Related Content

What's hot

Similar to Pune Clojure Course Outline

Recently uploaded

Pune Clojure Course Outline