Seven More Languages in Seven Weeks （读书笔记）：Julia

Julia

Day 1
julia> typeof(5)
~0 位取反
5 $ 6 //=> 3
implicit = {:a => 1, :b => 2, :c => 3}
explicit = [:a => 1, :b => 2, :c => 3] //静态类型限定？
Float64[1, 2, 3] //有点Go语言语法的味道？
切片：animals[2:end]
多维数组：A = [1 2 3; 4 5 6; 7 8 9] //Matlab？
v .* [0.5; 1.2; 0.1] //点乘
v' * v //内积

Day 2
for a = [1, 2, 3] println("$a") end //这个字符串求值借用的Perl语法？
abstract Story
type Book <: Story ... end //没有指定成员的类型？
super(Book)
subtypes(Story)
numbers = 1:10
+(numbers...)
In Julia, each version of a function is called a method, 但‘不属于特定的类型’？==>
Multiple dispatch
并发：
addprocs(2)
r1 = remotecall(2, rand, 10000000) //嗯？可以直接发起远程调用？
rand_list = fetch(r1) //阻塞等待结果返回（感觉这里的语法有点太原始的，不过适合于数值计算的使用场景）

@parallel (+) for i = 1:times ... end //循环并行化？
Interview with Julia’s Founders: Jeff Bezanson, Stefan Karpinski, Viral Shah, Alan Edelman
Julia注重性能（CPU计算速度、内存布局）？

Day 3
e = :(println("Hello!"))
typeof(e) //=> Expr
(e.head, e.args) //=> (:call,{:println,"Hello!"}) 又是Lisp风格的代码结构表示？
macro unless(t, b) quote ... end end //注意，Julia代码不需要写‘return’
julia> Pkg.add("Images") //靠，在线的包管理，这个牛
感觉Julia可以直接当作命令行的Matlab来用了？正如R语言对于S

http://media.pragprog.com/titles/7lang/code/julia/Codec.jl （代码略）
julia> using Codec
julia> freqs = Codec.blockdct6(img)
img2 = Codec.blockidct(freqs)

Weaknesses
The first is its youth, and the second is the lack of available packages（这个，-_-）

As Graydon Hoare, creator of the Rust language, puts it, Julia is a “Goldilocks language.” It’s just right.