Ratings and Reviews of Online Casinos
1. Sol Casino
Free Sign-Up Bonus: 20 Free Spins ( Free Sign-Up Bonus Link )
First Deposit Bonus: 100% up to €/$ 500 ( Registration Link )
2. Fresh Casino
Free Sign-Up Bonus: 30 Free Spins ( Free Sign-Up Bonus Link )
First Deposit Bonus: 200% up to €/$ 500 ( Registration Link )
3. Jet Casino
Free Sign-Up Bonus: 80 Free Spins ( Free Sign-Up Bonus Link )
First Deposit Bonus: 100% up to €/$ 200 ( Registration Link )
Crystal’s syntax is heavily inspired by Ruby’s, so it feels natural to read and easy to write, and has the added benefit of a lower learning curve for experienced Ruby devs.
# A very basic HTTP server require “http/server”
server = HTTP::Server.new do |context| context.response.content_type = “text/plain” context.response.print “Hello world, got #context.request.path!” end
puts “Listening on http://127.0.0.1:8080” server.listen(8080)
Start learning Crystal with the Language Reference
Crystal is statically type checked, so any type errors will be caught early by the compiler rather than fail on runtime. Moreover, and to keep the language clean, Crystal has built-in type inference, so most type annotations are unneeded.
def shout(x) # Notice that both Int32 and String respond_to `to_s` x.to_s.upcase end
foo = ENV[“FOO”]? || 10
typeof(foo) # => (Int32 | String) typeof(shout(foo)) # => String
Read more about Crystal’s type system
Null reference checks
All types are non-nilable in Crystal, and nilable variables are represented as a union between the type and nil. As a consequence, the compiler will automatically check for null references in compile time, helping prevent the dreadful billion-dollar mistake.
if rand(2) > 0 my_string = “hello world” end
Running the previous file:
$ crystal hello_world.cr Error in hello_world.cr:5: undefined method ‘upcase’ for Nil (compile-time type is (String | Nil))
puts my_string.upcase ^~~~~~
Crystal’s answer to metaprogramming is a powerful macro system, which ranges from basic templating and AST inspection, to types inspection and running arbitrary external programs.
class Object def has_instance_var?(name) : Bool @type.instance_vars.map &.name.stringify .includes? name end end
person = Person.new “John”, 30 person.has_instance_var?(“name”) #=> true person.has_instance_var?(“birthday”) #=> false
Read more about macros
Crystal uses green threads, called fibers, to achieve concurrency. Fibers communicate with each other using channels, as in Go or Clojure, without having to turn to shared memory or locks.
channel = Channel(Int32).new total_lines = 0 files = Dir.glob(“*.txt”)
files.each do |f| spawn do lines = File.read_lines(f) channel.send lines.size end end
files.size.times do total_lines += channel.receive end
Read more about Crystal’s concurrency model
Crystal has a dedicated syntax to easily call native libraries, eliminating the need to reimplement low-level tasks.
# Fragment of the BigInt implementation that uses GMP @[Link(“gmp”)] lib LibGMP alias Int = LibC::Int alias ULong = LibC::ULong
struct MPZ _mp_alloc : Int32 _mp_size : Int32 _mp_d : ULong* end
fun init_set_str = __gmpz_init_set_str(rop : MPZ*, str : UInt8*, base : Int) : Int fun cmp = __gmpz_cmp(op1 : MPZ*, op2 : MPZ*) : Int end
struct BigInt < Int def initialize(str : String, base = 10) err = LibGMP.init_set_str(out @mpz, str, base) raise ArgumentError.new(“invalid BigInt: #str”) if err == -1 end
def <=>(other : BigInt) LibGMP.cmp(mpz, other) end end
Learn how to bind to C libraries
Crystal libraries are packed as Shards, and distributed via Git without needing a centralised repository. Built in commands allow dependencies to be easily specified through a YAML file and fetched from their respective repositories.
name: my-project version: 0.1 license: MIT
dependencies: mysql: github: crystal-lang/crystal-mysql
Read more about Shards in the repo