asterite

deps do
  github "manastech/frank"
end

asterite

alias RecursiveArray = Int32 | Array(RecursiveArray)

a = [1, 2, 3] of RecursiveArray
a << a
p a

asterite

Crystal's type inference algorithm

The type inference starts at type_inference.cr. Here, the program's AST is visited with a TypeVisitor. This visitor's does many things:

1. It declares classes and defs (when the visitor visits a ClassDef node it declares a class, etc.). Note that the visitor doesn't visits a def's contents.
2. It types literals. For example the number 1, represented by a NumberLiteral node, is assigned the type Int32. Every ASTNode has a type, which initially is nil.
3. It keeps track of variables defined a method (or at the top level) and their types. For example, when the visitor finds an assignment like a = 1 it first visits 1 and assigns the type Int32 to it. Then it binds the node a to the

asterite

class Array(T)
  def map(&block : T -> U)
    ary = [] of U
    each { |e| ary << yield e }
    ary
  end
end

class Foo
end

asterite

# Ported from Rust from https://gist.github.com/joshmarinacci/c84d0979e100d107f685

record Vector, x, y, z do
  def scale(s)
    Vector.new(x * s, y * s, z * s)
  end

  def +(other)
    Vector.new(x + other.x, y + other.y, z + other.z)
  end

asterite

struct Enum
  include Comparable(self)

  macro def to_s(io : IO) : Nil
    {% if @enum_flags %}
      found = false
      {% for member in @enum_members %}
        if value & {{member}}.value != 0
          io << ", " if found
          io << {{member.stringify}}

asterite

require "json"

class Object
  macro json_schema(properties)
    {% for key, value in properties %}
      property :{{key.id}}
    {% end %}

    def self.new(_pull : Json::PullParser)
      {% for key, value in properties %}

asterite

def foo(&block)
  block
end

block = foo do
  {0, 0, 42, 0}
end
block.call

asterite

class Context
  def initialize
    @x = self
  end

  def x
    @x
  end

  def it(&block)

asterite

require "compiler/crystal/**"

include Crystal

class MyVisitor < Visitor
  def initialize
    @str = StringIO.new
  end

  def visit(node : ClassDef)