Open Source Software and Culture -- Crystal

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3VCZ say = "I love Ruby" puts say #=> I
love Ruby say['love'] = "*love*" puts say.upcase #=> I *LOVE* RUBY # "I *love* Ruby" in five times 5.times { puts say }

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a = A() add1(a) IUUQXQIPNFTTPJDJOEJBOBFEVKTJFLXIBUJTHSBEVBMUZQJOH

def add1(x): return x + 1 class A(object): pass a
= A() add1(a) # TypeError: unsupported operand type(s) for +: 'A' and ‘int' # (Interpreter) (SBEVBM5ZQJOH IUUQXQIPNFTTPJDJOEJBOBFEVKTJFLXIBUJTHSBEVBMUZQJOH

(SBEVBM5ZQJOH class A { int add1(int x) { return x
+ 1; } public static void main(String args[]) { A a = new A(); add1(a); } } IUUQXQIPNFTTPJDJOEJBOBFEVKTJFLXIBUJTHSBEVBMUZQJOH

+ 1; } public static void main(String args[]) { A a = new A(); add1(a); } } IUUQXQIPNFTTPJDJOEJBOBFEVKTJFLXIBUJTHSBEVBMUZQJOH # add1(int) in A cannot be applied to (A) add1(a); # (Compiler)

+ 1; } public static void main(String args[]) { A a = new A(); if (false) add1(a); } } IUUQXQIPNFTTPJDJOEJBOBFEVKTJFLXIBUJTHSBEVBMUZQJOH

+ 1; } public static void main(String args[]) { A a = new A(); if (false) add1(a); } } IUUQXQIPNFTTPJDJOEJBOBFEVKTJFLXIBUJTHSBEVBMUZQJOH # add1(int) in A cannot be applied to (A) add1(a);

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a = A() add1(a) IUUQXQIPNFTTPJDJOEJBOBFEVKTJFLXIBUJTHSBEVBMUZQJOH

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(SBEVBM5ZQJOH def add1(x : ?): return x + 1 add1(1)
# int ~> ? IUUQXQIPNFTTPJDJOEJBOBFEVKTJFLXIBUJTHSBEVBMUZQJOH

(SBEVBM5ZQJOH def g(p : int * int): return p[0] def
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(SBEVBM5ZQJOH int ~ int int !~ bool
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)FMMPXPSME /* Java: Main.java */ public class Main { public
static void main(String[] args) { System.out.println("Hello world!"); } }

)FMMPXPSME /* C: main.c */ #include <stdio.h> int main() {
puts("Hello world!"); return 0; }

)FMMPXPSME # Crystal: main.cr p "Hello world!"

4JNQMF def say_hello() puts("Hello world!"); end say_hello();

4JNQMF def say_hello() puts("Hello world!") end say_hello()

4JNQMF def say_hello puts "Hello world!" end say_hello

%ZOBNJDBMMZUZQFE def prime?(n) (2...n).all? { |i| n % i !=
0 } end # Prime pairs that differ from six def sexy_primes(n) (9..n).map { |i| { i - 6, i } } .select { |i| i.all? { |x| prime?(x) } } end puts sexy_primes(100_000)

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5ZQFDIFDLJOH def prime?(n) (2...n).all? { |i| n % i !=
0 } end def sexy_primes(n) (9..n).map { |i| { i - 6, i } } .select { |i| i.all? { |x| prime?(x) } } end puts sexy_primes(100_000)

0 } end def sexy_primes(n) (9..n).map { |i| { i - 6, i } } .select { |i| i.all? { |x| prime?(x) } } end puts sexy_primes("Oops")

0 } end def sexy_primes(n) (9..n).map { |i| { i - 6, i } } .select { |i| i.all? { |x| prime?(x) } } end puts sexy_primes("Oops") # Error: no overload matches `Int32#<` with type String

0 } end def sexy_primes(n) (9..n).map { |i| { i - 6, i } } .select { |i| i.all? { |x| prime?(x) } } end puts sexy_primes("Oops") sexy_primes # Error: no overload matches `Int32#<` with type String

0 } end def sexy_primes(n) (9..n).map { |i| { i - 6, i } } .select { |i| i.all? { |x| prime?(x) } } end puts sexy_primes("Oops") map sexy_primes # Error: no overload matches `Int32#<` with type String

0 } end def sexy_primes(n) (9..n).map { |i| { i - 6, i } } .select { |i| i.all? { |x| prime?(x) } } end puts sexy_primes(100_000)

0 } end def sexy_primes(n : Int) (9..n).map { |i| { i - 6, i } } .select { |i| i.all? { |x| prime?(x) } } end puts sexy_primes(100_000)

0 } end def sexy_primes(n : Int) (9..n).map { |i| { i - 6, i } } .select { |i| i.all? { |x| prime?(x) } } end puts sexy_primes("Oops")

0 } end def sexy_primes(n : Int) (9..n).map { |i| { i - 6, i } } .select { |i| i.all? { |x| prime?(x) } } end puts sexy_primes("Oops") # Error: no overload matches `sexy_primes` with type String

)JHIMFWFM numbers = [1, 2, 3, 4] puts numbers.map {
|x| x + 10 } #=> [11, 12, 13, 14] puts numbers[0] + numbers[-1] #=> 5 phones = { "Ann" => "0987654321", "Bob" => "0223456789" } puts phones["Bob"] #=> "0223456789"

)JHIMFWFM objects = [0, "one", { 2, "three" }] objects
<< 456 puts typeof(objects) #=> Array(String | Int32 | {Int32, String}) objects << 78.9 #=> no overload matches 'Array(String | Int32 | {Int32, String})#<<' with type Float64

-PXMFWFM ptr = Pointer(UInt8).malloc(20) ptr.value = 10_u8 puts ptr #=>
Pointer(UInt8)@0x255a440 a = 1 ptr = pointerof(a) ptr.value = 2 puts a #=> 2 buffer = uninitialized UInt8[1024] # allocated on the stack

-PXMFWFM /* C: math.c */ #include <stdio.h> #include <stdlib.h> /*
export function */ EXPORT double cos(double x) { /* return cos(x) */ }

-PXMFWFM @[Link("math")] lib LibMath fun cos(value : Float64) : Float64
end puts LibMath.cos(1.5) #=> 0.0707372

.BDSP macro define_method(name, content) def {{name}} {{content}} end end define_method
foo, 1 puts foo

.BDSP def foo 1 end puts foo #=> 1

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Open Source Software and Culture -- Crystal

Open Source Software and Culture -- Crystal

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