This slide is presented in Tech Talk in Rakuten on March 28, 2014. Egison is the world's first programming language that realized non-linear pattern-matching with backtracking. We can directly represent pattern-matching against lists, multisets, sets, trees, graphs and any kind of data types. Egison makes programming dramatically simple!

1. The Egison Programming Language
Vol.01 Mar/28/2014
Satoshi Egi
Rakuten Institute of Technology
http://rit.rakuten.co.jp/

2. 2
Profile of Egison
Paradigm Pattern-matching-oriented,
Pure functional
Author Satoshi Egi
License MIT
Version 3.3.4 (2014/03/28)
First Released 2011/5/24
Filename Extension .egi
Implemented in Haskell (about 3,400 lines)
Egison is the programming language I’ve created.

3. 3
Motivation
I’d like to create a programming language that
directly represents human’s intuition.
Function modularity
Type system Pattern matching
Egison (current)
Egison next version
Function modularity
Type system Pattern matching
Lisp (before Scheme)
Scheme
ML, OCaml, Haskell

4. 4
Egison in one minute
Egison is the world's first programming language
that realized non-linear pattern-matching with
backtracking.
(match-all xs (multiset integer)
[<cons $x <cons ,x _>> x])
Egison
Enumerate the elements of
the collection ‘xs’ that appear
more than twice
pairs = []
(1..n).each do |i|
(i..n).each do |j|
if xs[i] == xs[j]
pair = xs[i]
end
end
end
Ruby

5. 5
Quick Tour

6. 6
The ‘match-all’ expression
Target Matcher
Pattern Expression executed
when pattern matching
succeed
Result
Meaning: Pattern match against the “target” as
the “matcher” with the “pattern” and return all
results of pattern matching.

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The ‘match-all’ expression
Target
Pattern-match against the target data {1 1 2 3 2}

8. 8
The ‘match-all’ expression
MatcherTarget
Pattern-match against the target data {1 1 2 3 2}
as the multiset of integers

9. 9
The ‘match-all’ expression
Target Matcher
Pattern
Pattern-match against the target data {1 1 2 3 2}
as the multiset of integers with the pattern
<cons $x <cons ,x _>>

10. 10
The ‘match-all’ expression
Target Matcher
Pattern Expression executed
when pattern matching
succeed
Pattern-match against the target data {1 1 2 3 2}
as the multiset of integers with the pattern
<cons $x <cons ,x _>> and return the value
bound to x.

11. 11
The ‘match-all’ expression
Target Matcher
Pattern Expression executed
when pattern matching
succeed
Result
Pattern-match against the target data {1 1 2 3 2}
as the multiset of integers with the pattern
<cons $x <cons ,x _>> and return the value
bound to x.

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The ‘cons’ pattern constructor
Divide a collection into an element and a
collection of rest of elements.

13. 13
The ‘cons’ pattern constructor
The meaning of ‘cons’ changes for each matcher
Divide a collection into an element and a
collection of rest of elements.

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The nested ‘cons’ pattern constructor
Extracting two elements using the ‘cons’ patterns.

15. 15
Non-linear patterns
Elements that appear twice
Two same head elements
We can deal with the multiple occurrences of the
same variables in a pattern.

16. 16
The ‘join’ pattern constructor
Divide a collection into two collections.

17. 17
Playing with the ‘join’ pattern constructor
Enumerate all two combination of elements.

18. 18
Demonstrations

19. 19
The first application of Egison

20. 20
The first application of Egison
Match as a set of cards

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The first application of Egison
Pattern for straight flash

22. 22
The pattern for straight flush

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The pattern for straight flush
Same suit with $s

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The pattern for straight flush
Same suit with $s
Numbers are serial from
$n

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The pattern for straight flush
Same suit with $s
Numbers are serial from
$n
We can write any expression after ‘,’

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The first application of Egison
Pattern for two pair

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The pattern for two pair

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The pattern for two pair
Matches with any suit
Matches with any card

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The pattern for two pair
Matches with any suit
Matches with any card
Same number with $m
Same number with $n

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The pattern for two pair
Matches with any suit
Matches with any card
Same number with $m
Same number with $n
Non-linear patterns have very strong power

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The first application of Egison
Non-linear patterns enables to
represent all hands in a single pattern

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The first application of Egison
Egisonists can write this
code in 2 minutes!
Non-linear patterns enables to
represent all hands in a single pattern

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Java version
public static boolean hasPair(Card[] cards) {
for (int i = 0; i <= 4 ;i++) {
for (int j = i + 1 ; j <= 4 ; j++) {
if (cards[i] == (cards[j])) {
return true;
}
return false;
}
}
}
Just finding a pair of cards is already complex.
I found a poker-hand evaluator in Java more than
200 lines of code.
http://www.codeproject.com/Articles/38821/Make-a-poker-hand-evalutator-in-Java

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More complex example, Mahjong

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More complex example, Mahjong
Two same tiles
Three consecutive tiles
Three same tiles

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More complex example, Mahjong
Two same tiles
Three consecutive tiles
Three same tiles
Seven twins or one twin + four shuntsu or kohtsu

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More complex example, Mahjong
Two same tiles
Three consecutive tiles
Three same tiles
Seven twins or one twin + four shuntsu or kohtsu
Pattern modularization makes
programming more simple!

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One More Exciting Demonstration

39. 39
Collections

40. 40
Infinite collections

41. 41
Beautiful example on elementary mathematics
Pattern matching against an infinite collection

42. 42
This sample is on the homepage of Egison

43. 43
Egison design policy
Beautiful and Elegant
-> Simple

44. 44
Visions

45. 45
What we will be able to do with Egison
• Access data in new elegant ways
• The most elegant query language
• Able to access lists, sets, graphs, trees or any
other data in a unified way
• Analyze data in new elegant ways
• Provide a way to access various algorithm and
data structures in a unified way
• Implement new interesting applications
e.g.
• Natural language processing, New programming
languages, Mathematical expression handling,
Image processing

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What we will be able to do with Egison
• Access data in new elegant ways
• The most elegant query language
• Able to access lists, sets, graphs, trees or any
other data in a unified way
• Analyze data in new elegant ways
• Provide a way to access various algorithm and
data structures in a unified way
• Implement new interesting applications
e.g.
• Natural language processing, New programming
languages, Mathematical expression handling,
Image processing
Stage1
Stage2

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What we will be able to do with Egison
• Access data in new elegant ways
• The most elegant query language
• Able to access lists, sets, graphs, trees or any
other data in a unified way
• Analyze data in new elegant ways
• Provide a way to access various algorithm and
data structures in a unified way
• Implement new interesting applications
e.g.
• Natural language processing, New programming
languages, Mathematical expression handling,
Image processing
Stage1
Stage2

48. 48
Query example
• Query that returns twitter users who are
followed by “__Egi” but not follow back
“__Egi”.
id integer
name string
User:
from_id integer
to_id Integer
Follow:

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SQL version
• Complex and difficult to understand
• Complex where clause contains “NOT EXIST”
• Subquery

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Egison version
• Very Simple
• No where clauses
• No subquery

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Egison version
• Very Simple
• No where clauses
• No subquery
Joining 4 tables

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Egison version
• Very Simple
• No where clauses
• No subquery
Joining 4 tables
1. Get id of “__Egi”

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Egison version
• Very Simple
• No where clauses
• No subquery
Joining 4 tables
1. Get id of “__Egi”
2. Followed by ‘uid’

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Egison version
• Very Simple
• No where clauses
• No subquery
Joining 4 tables
1. Get id of “__Egi”
2. Followed by ‘uid’
3. But not follow backnot

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Egison version
• Very Simple
• No where clauses
• No subquery
Joining 4 tables
1. Get id of “__Egi”
2. Followed by ‘uid’
3. But not follow backnot
4. Get name of ‘fid’

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Egison version
• Very Simple
• No where clauses
• No subquery
Joining 4 tables
1. Get id of “__Egi”
2. Followed by ‘uid’
3. But not follow backnot
4. Get name of ‘fid’
Return the results

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Egison version
• Very Simple
• No where clauses
• No subquery
Joining 4 tables
1. Get id of “__Egi”
2. Followed by ‘uid’
3. But not follow backnot
4. Get name of ‘fid’
Return the results
We can run this query against
data in SQLite!

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GUI frontend
• We’ll provide GUI for intuitive data access
• Data access for even non-engineers
• Engineers can concentrate on data analysis
Very Easy!

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What we will be able to do with Egison
• Access data in new elegant ways
• The most elegant query language
• Able to access lists, sets, graphs, trees or any
other data in a unified way
• Analyze data in new elegant ways
• Provide a way to access various algorithm and
data structures in a unified way
• Implement new interesting applications
e.g.
• Natural language processing, New programming
languages, Mathematical expression handling,
Image processing
Stage1
Stage2

60. 60
Database in the next age
In future, databases will be
embedded in programming
languages and hidden.
We will be able to handle
databases directly and
easily as arrays and
hashes in existing
languages.
The pattern-matching of Egison will play a
necessary role for this future.

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The other funny plans
• Access data in new elegant ways
• The most elegant query language
• Able to access lists, sets, graphs, trees or any
other data in a unified way
• Analyze data in new elegant ways
• Provide a way to access various algorithm and
data structures in a unified way
• Implement new interesting applications
e.g.
• Natural language processing, New programming
languages, Mathematical expression handling,
Image processing
Stage1
Stage2

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Egison has wide range of applications
• Data mining
• Work as the most elegant query language
• Natural Language Processing
• Enable to handle complex syntax structures
intuitively as humans do in their mind
• New Programming Languages
• Mathematical expression handling
• Enable to handle complex structures easily
• Enable to handle various mathematical notion
directly
Egison is an inevitable and necessary
innovation in the history of computer science

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The Current Situation

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Egison website

65. 65
Online demonstrations

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Installer of Egison and ‘egison-tutorial’
• Egison can be installed on Mac, Windows and Linux.
• We’ve prepared a package for Mac
• Download it from http://www.egison.org
Install me Egison
and please try
‘egison-tutorial’!
Get following commands!
• egison
• egison-tutorial

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‘egison-tutorial’
You’ll get Egison
easily!

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‘egison-tutorial’
We can try it
online, too!

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Next Plans

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Egison as the programming language
Function modularity
Type system Pattern matching
Egison (current)
Egison next version
Function modularity
Type system Pattern matching
Lisp (before Scheme)
Scheme
ML, OCaml, Haskell
Make Egison the perfect programming language.

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Extending other languages
• Ruby https://github.com/egison/egison-ruby
• Python (planning)
• Haskell (planning)

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Poker hands in Ruby

73. 73
Database support
I appreciate your request for support !
We will extend support for high speed data
storages as the backend of Egison.

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Thank you!
Please visit our website!
http://www.egison.org
Follow us in Twitter @Egison_Lang
Let’s talk and collaborate with us!
satoshi.egi@mail.rakuten.com