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
Crystal Clean
Search
Luís Ferreira
January 22, 2015
Technology
2
220
Crystal Clean
An overview of the Crystal programming language, with a lot of comparisons with Ruby.
Luís Ferreira
January 22, 2015
Tweet
Share
More Decks by Luís Ferreira
See All by Luís Ferreira
Winter is coming
zamith
0
750
SI - Module5
zamith
0
76
Design Sprints
zamith
0
160
Continuous learning, teaching and the art of improving yourself
zamith
0
140
Clean Code
zamith
3
200
The best language I have ever learned.
zamith
3
1.6k
Testing Magic
zamith
3
1.5k
Clean Code
zamith
7
1.6k
Other Decks in Technology
See All in Technology
ユニットテストに対する考え方の変遷 / Everyone should watch his live coding
mdstoy
0
130
BirdCLEF+2025 Noir 5位解法紹介
myso
0
200
JAZUG 15周年記念 × JAT「AI Agent開発者必見:"今"のOracle技術で拡張するAzure × OCIの共存アーキテクチャ」
shisyu_gaku
0
130
LLM時代にデータエンジニアの役割はどう変わるか?
ikkimiyazaki
4
920
神回のメカニズムと再現方法/Mechanisms and Playbook for Kamikai scrumat2025
moriyuya
4
600
Goに育てられ開発者向けセキュリティ事業を立ち上げた僕が今向き合う、AI × セキュリティの最前線 / Go Conference 2025
flatt_security
0
350
SoccerNet GSRの紹介と技術応用:選手視点映像を提供するサッカー作戦盤ツール
mixi_engineers
PRO
1
190
スタートアップにおけるこれからの「データ整備」
shomaekawa
1
240
Escaping_the_Kraken_-_October_2025.pdf
mdalmijn
0
150
AWS 잘하는 개발자 되기 - AWS 시작하기: 클라우드 개념부터 IAM까지
kimjaewook
0
110
AWSにおけるTrend Vision Oneの効果について
shimak
0
130
社内報はAIにやらせよう / Let AI handle the company newsletter
saka2jp
7
990
Featured
See All Featured
Rebuilding a faster, lazier Slack
samanthasiow
84
9.2k
Documentation Writing (for coders)
carmenintech
75
5k
No one is an island. Learnings from fostering a developers community.
thoeni
21
3.5k
GitHub's CSS Performance
jonrohan
1032
460k
JavaScript: Past, Present, and Future - NDC Porto 2020
reverentgeek
52
5.6k
Balancing Empowerment & Direction
lara
4
680
I Don’t Have Time: Getting Over the Fear to Launch Your Podcast
jcasabona
33
2.5k
Principles of Awesome APIs and How to Build Them.
keavy
127
17k
The Success of Rails: Ensuring Growth for the Next 100 Years
eileencodes
46
7.6k
Code Review Best Practice
trishagee
72
19k
Why Our Code Smells
bkeepers
PRO
339
57k
実際に使うSQLの書き方 徹底解説 / pgcon21j-tutorial
soudai
PRO
189
55k
Transcript
CRYSTAL by Luís Zamith
Efficient, Ruby like language FEATURES
Static checks FEATURES
Macros FEATURES
Simple C bindings FEATURES
WARNING! Pre-Alpha
def fib(n)! if n < 3! 1! else! fib(n-1) +
fib(n-2)! end! end! ! fib(35)
RUBY def fib(n)! if n < 3! 1! else! fib(n-1)
+ fib(n-2)! end! end! ! fib(35)
CRYSTAL def fib(n)! if n < 3! 1! else! fib(n-1)
+ fib(n-2)! end! end! ! fib(35)
Calculating ------------------------------------- ruby 1.000 i/100ms crystal 2.000 i/100ms ----------------------------------------------------- ruby
1.268 (± 0.0%) i/s - 13.000 crystal 26.321 (± 3.8%) i/s - 264.000 ! Comparison: crystal: 26.3 i/s ruby: 1.3 i/s - 20.75x slower
RUBY class Email! attr_reader :subject, :date, :from! ! def initialize(subject,
date: "", from: "")! @subject = subject! @date = date! @from = from! end! ! def to_s ! “Date: #{date}! From: #{from}! Subject: #{subject}”! end! end
CRYSTAL class Email! getter :subject, :date, :from! ! def initialize(subject,
options = {} of Symbol => String)! @subject = subject! @date = options.fetch(:date, "")! @from = options.fetch(:from, "")! end! ! def to_s(io: IO)! io << "Date: #{date}\n! ! ! ! ! ! ! ! From: #{from}\n! Subject: #{subject}\n\n"! end! end
CRYSTAL class Email! getter :subject, :date, :from! ! def initialize(subject,
options = {} of Symbol => String)! @subject = subject! @date = options.fetch(:date, "")! @from = options.fetch(:from, "")! end! ! def to_s(io: IO)! io << "Date: #{date}\n! ! ! ! ! ! ! ! From: #{from}\n! Subject: #{subject}\n\n"! end! end
CRYSTAL class Email! getter :subject, :date, :from! ! def initialize(subject,
options = {} of Symbol => String)! @subject = subject! @date = options.fetch(:date, "")! @from = options.fetch(:from, "")! end! ! def to_s(io: IO)! io << "Date: #{date}\n! ! ! ! ! ! ! ! From: #{from}\n! Subject: #{subject}\n\n"! end! end
CRYSTAL class Email! getter :subject, :date, :from! ! def initialize(subject,
options = {} of Symbol => String)! @subject = subject! @date = options.fetch(:date, "")! @from = options.fetch(:from, "")! end! ! def to_s(io: IO)! io << "Date: #{date}\n! ! ! ! ! ! ! ! From: #{from}\n! Subject: #{subject}\n\n"! end! end
Static Checks
RUBY def string_size(str)! puts str.length! end! ! string_size("This is a
string")! string_size(nil) 16 `string_size': undefined method `length' for nil:NilClass (NoMethodError)
CRYSTAL def string_size(str)! puts str.length! end! ! string_size("This is a
string")! string_size(nil) instantiating 'string_size(Nil)' undefined method 'length' for Nil
Special getters
CRYSTAL class Email! getter! :subject, :date, :from! ! ...! end!
! email = Email.new("Homework this week", { date: nil, from: "Ferdous" }),! ! p email.date? # nil
CRYSTAL class Email! getter! :subject, :date, :from! ! ...! end!
! email = Email.new("Homework this week", { date: nil, from: "Ferdous" }),! ! p email.date
CRYSTAL class Email! getter! :subject, :date, :from! ! ...! end!
! email = Email.new("Homework this week", { date: nil, from: "Ferdous" }),! ! p email.date Nil assertion failed
CRYSTAL class Email! getter? :subject, :date, :from! ! ...! end!
! email = Email.new("Homework this week", { date: nil, from: "Ferdous" }),! ! p email.date? # nil
CRYSTAL class Email! getter? :subject, :date, :from! ! ...! end!
! email = Email.new("Homework this week", { date: nil, from: "Ferdous" }),! ! p email.date
CRYSTAL class Email! getter? :subject, :date, :from! ! ...! end!
! email = Email.new("Homework this week", { date: nil, from: "Ferdous" }),! ! p email.date undefined method 'date' for Email (did you mean 'date?'?)
Macros
RUBY class BasicObject! def self.attr_reader(*names)! names.map(&:to_s).each do |name|! class_eval "!
def #{name}! @#{name}! end! "! end! end! end
CRYSTAL class Object! macro getter(*names)! {% for name in names
%}! {% name = name.var if name.is_a?(DeclareVar) %}! ! def {{name.id}}! @{{name.id}}! end! {% end %}! end! end
C bindings
RUBY Not very simple to connect ! Need to write
C ! Need to know Ruby’s C implementation (struct, methods, etc…)
CRYSTAL lib C! fun atoi(str : UInt8*) : Int32! end!
! p C.atoi(“28").class # Int32
CRYSTAL @[Link("readline")]! lib LibReadline! fun readline(prompt : UInt8*) : Pointer(UInt8)!
end! ! line = LibReadline.readline("What's your name?\n")! p String.new(line) # What’s your name?! # zamith! # ”zamith"
Generics
RUBY class Foo! attr_reader :value! ! def initialize(value)! @value =
value! end! end! ! foo = Foo.new(1)! p foo.value.abs # 1! ! foo = Foo.new('a')! p foo.value.ord # 97
CRYSTAL class Foo! getter :value! ! def initialize(@value); end! end!
! foo = Foo.new(1)! p foo.value.abs # 1! ! foo = Foo.new(‘a’)! p foo.value.ord # undefined method 'abs' for Char
CRYSTAL class Foo(T)! getter :value! ! def initialize(@value : T);
end! end! ! foo = Foo.new(1)! p foo.value.abs # 1! ! foo = Foo.new('a')! p foo.value.ord # 97
CRYSTAL class Array(T)! include Enumerable! include Comparable(Array)! ! def initialize(size,
value : T)! ! ! . . .! end! end arr = [1, 2]! arr.first.abs! ! arr = [1, '2']! arr.first.abs # error!
Specs
CRYSTAL require "spec"! ! class MyString! def initialize(@string); end! !
def size! @string.size! end! end! ! describe "Repo" do! describe "size" do! it "returns the size of my string" do! MyString.new("Hello").size.should eq 5! end! end! end
Notable Misses
CRYSTAL Single quoted strings ! require_relative ! keyword arguments !
send method_missing ! define_method ! eval
Interesting Things
CRYSTAL RUBY [1,2].map &.to_s.+(“ hello”) [1,2].map do |num| ! !
num.to_s.+(" hello”)! end # [“1 hello", "2 hello"] # [“1 hello", "2 hello"]
CRYSTAL class Hash(K, V)! ...! def self.new(comp = StandardComparator, &block
: (Hash(K, V), K -> V))! new block, comp! end! ! def self.new(default_value : V, comp = StandardComparator)! new(comp) { default_value }! end! ! def self.new(comparator)! new nil, comparator! end! ...! end
CRYSTAL class Hash(K, V)! ...! def self.new(default_value = nil :
V, comp = StandardComparator)! new(comp) { default_value }! end! ...! end
CRYSTAL class Hash(K, V)! ...! def self.new(default_value = nil :
V?, comp = StandardComparator)! new(comp) { default_value }! end! ...! end
CRYSTAL - DEPENDENCIES
DEMO