Upgrade to Pro
— share decks privately, control downloads, hide ads and more …
Speaker Deck
Features
Speaker Deck
PRO
Sign in
Sign up for free
Search
Search
Functional Programming and Ruby - EuRuKo
Search
Pat Shaughnessy
June 28, 2013
Technology
2
770
Functional Programming and Ruby - EuRuKo
Slides from Athens, June 2013
Pat Shaughnessy
June 28, 2013
Tweet
Share
More Decks by Pat Shaughnessy
See All by Pat Shaughnessy
20000 Leagues Under ActiveRecord
pat_shaughnessy
0
120
Visualizing Garbage Collection in Rubinius, JRuby and Ruby 2.0
pat_shaughnessy
8
710
Functional Programming and Ruby
pat_shaughnessy
6
1.5k
Dissecting a Ruby Block
pat_shaughnessy
10
440
Other Decks in Technology
See All in Technology
毎晩の 負荷試験自動実行による効果
recruitengineers
PRO
5
180
Introduction to Sansan, inc / Sansan Global Development Center, Inc.
sansan33
PRO
0
2.7k
All About Sansan – for New Global Engineers
sansan33
PRO
1
1.2k
ポストコロナ時代の SaaS におけるコスト削減の意義
izzii
1
470
ロールが細分化された組織でSREは何をするか?
tgidgd
1
420
cdk initで生成されるあのファイル達は何なのか/cdk-init-generated-files
tomoki10
1
670
microCMSではじめるAIライティング
himaratsu
0
150
20250708オープンエンドな探索と知識発見
sakana_ai
PRO
4
1k
United™️ Airlines®️ Customer®️ USA Contact Numbers: Complete 2025 Support Guide
flyunitedguide
0
800
Amazon SNSサブスクリプションの誤解除を防ぐ
y_sakata
3
190
〜『世界中の家族のこころのインフラ』を目指して”次の10年”へ〜 SREが導いたグローバルサービスの信頼性向上戦略とその舞台裏 / Towards the Next Decade: Enhancing Global Service Reliability
kohbis
3
1.5k
SRE with AI:実践から学ぶ、運用課題解決と未来への展望
yoshiiryo1
0
300
Featured
See All Featured
XXLCSS - How to scale CSS and keep your sanity
sugarenia
248
1.3M
jQuery: Nuts, Bolts and Bling
dougneiner
63
7.8k
Bash Introduction
62gerente
613
210k
Building a Modern Day E-commerce SEO Strategy
aleyda
42
7.4k
Designing Dashboards & Data Visualisations in Web Apps
destraynor
231
53k
Large-scale JavaScript Application Architecture
addyosmani
512
110k
Keith and Marios Guide to Fast Websites
keithpitt
411
22k
Embracing the Ebb and Flow
colly
86
4.8k
The Cult of Friendly URLs
andyhume
79
6.5k
Performance Is Good for Brains [We Love Speed 2024]
tammyeverts
10
970
How to Create Impact in a Changing Tech Landscape [PerfNow 2023]
tammyeverts
53
2.9k
The Pragmatic Product Professional
lauravandoore
35
6.7k
Transcript
foo :: Ord a => [a] -> [a] foo []
= [] foo (p:xs) = (foo lesser) ++ [p] ++ (foo greater) where lesser = filter (< p) xs greater = filter (>= p) xs
None
Ruby is a language designed in the following steps: *
take a simple lisp language * add blocks, inspired by higher order functions * add methods found in Smalltalk * add functionality found in Perl So, Ruby was a Lisp originally, in theory. Let's call it MatzLisp from now on. ;-) ! ! ! ! ! ! ! matz.
None
None
None
None
Haskell... is a polymorphically statically typed, lazy, purely functional language,
quite different from most other programming languages. The language is named for Haskell Brooks Curry, ...
- what is “functional programming?” - higher order functions -
lazy evaluation - memoization
None
higher order functions
[1..10] =>[1, 2, 3, 4, 5, 6, 7, 8, 9,
10] (1..10).to_a
[ x*x | x <- [1..10]] (1..10).collect { |x| x*x
} =>[1, 4, 9, 16, 25, 36, 49, 64, 81, 100] (1..10).map { |x| x*x }
None
map (\x -> x*x) [1..10] (1..10).map &lambda { |x| x*x
} =>[1, 4, 9, 16, 25, 36, 49, 64, 81, 100] (1..10).map &(->(x) { x*x })
lazy evaluation
[1..] =>[1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28, 29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,50,51,52,53,54, 55,56,57,58,59,60,61,62,63,64,65,66,67,68,69,70,71,72,73,74,75,76,77,78,79,80, 81,82,83,84,85,86,87,88,89,90,91,92,93,94,95,96,97,98,99,100,101,102,103,104,1 05,106,107,108,109,110,111,112,113,114,115,116,117,118,119,120,121,122,123, etc...
take 10 [1..] =>[1,2,3,4,5,6,7,8,9,10]
take 10 [ x+1 | x <- [ x*x |
x <- [1..]]] =>[2,5,10,17,26,37,50,65,82,101]
(1..Float::INFINITY) .lazy .collect { |x| x*x } .collect { |x|
x+1 } .take(10).force =>[2,5,10,17,26,37,50,65,82,101]
=>[2,5,10,17,26,37,50,65,82,101] (1..Float::INFINITY) .lazy .collect { |x| x*x } .collect {
|x| x+1 } .first(10)
(1..10).collect { |x| x*x } each Range Enumerable #collect Enumerable#collect
enum = Enumerator.new do |y| y.yield 1 y.yield 2 end
p enum.collect { |x| x*x } => [1, 4] Enumerator
enum = Enumerator.new do |y| y.yield 1 y.yield 2 end
enum.collect do |x| x*x end
Enumerator Yielder yields Generator do |y| y.yield 1 y.yield 2
end
Enumerator::Lazy calls each yields Enumerator::Lazy calls each yields my block
my block yields yields
=>[2,5,10,17,26,37,50,65,82,101] (1..Float::INFINITY) .lazy .collect { |x| x*x } .collect {
|x| x+1 } .first(10)
Step 1: Call "each" Lazy Lazy x*x x+1 yield yield
Infinite range first(10) Step 2: yield to the blocks, one at a time
memoization
slow_fib 0 = 0 slow_fib 1 = 1 slow_fib n
= slow_fib (n-2) + slow_fib (n-1) map slow_fib [1..10] => [1,1,2,3,5,8,13,21,34,55] http://www.haskell.org/haskellwiki/Memoization
None
memoized_fib = (map fib [0 ..] !!) where fib 0
= 0 fib 1 = 1 fib n = memoized_fib (n-2) + memoized_fib (n-1) Typical Haskell magic! http://www.haskell.org/haskellwiki/Memoization
(map fib [0 ..] !!) Infinite, lazy list of return
values A curried function to return the requested fib
[0 ..] (0..Float::INFINITY)
map fib [0 ..] (0..Float::INFINITY) .lazy.map {|x| fib(x) }
(map fib [0 ..] !!) cache = (0..Float::INFINITY) .lazy.map {|x|
fib(x) } nth_element_from_list = lambda { |ary, n| ary[n]} nth_fib = nth_element_from_list.curry[cache]
map memoized_fib [1..10] => [1,1,2,3,5,8,13,21,34,55] `block in <main>': undefined method
`[]' for #<Enumerator::Lazy: #<Enumerator::Lazy: 0..Infinity>:map> (NoMethodError)
each Range Enumerable #collect (0..Float::INFINITY) .lazy.map {|x| fib(x) } nth_element_from_list
= lambda { |ary, n| ary[n]}
@cache = {} @cache[1] = 1 @cache[2] = 1 def
memoized_fib(n) @cache[n] ||= memoized_fib(n-1) + memoized_fib(n-2) end
learn by studying other languages... and acquire a different perspective
on Ruby
Ruby has many functional features, but is not a functional
language