structs

# A struct: named fields, a constructor, methods.

struct Point
  getter x : Int32
  getter y : Int32

  # `@x` is the field. Writing it in the parameter list assigns it.
  def initialize(@x : Int32, @y : Int32)
  end

  def +(other : Point) : Point
    Point.new(x + other.x, y + other.y)
  end

  def to_s : String
    "(#{x}, #{y})"
  end
end

a = Point.new(1, 2)
b = Point.new(3, 4)

puts a.x
puts (a + b).to_s

# A struct is a value: assigning it copies it.
c = a
puts c.to_s

Press Run.

recorded with iyi 0.18.0 (built on Crystal 1.22.0-dev [2a9653052] (2026-10-18)) · Linux 7.0.0-38-generic x86_64, QEMU Virtual CPU version 2.5+ · 2026-10-19

You can type in the pane: nothing here compiles, so what you type cannot run, and the page says which bytes it is running the moment the text stops being the recorded file. There is no standard input, no filesystem and no threads on this target, and one sample fails on purpose for exactly that reason.

Run executes structs.wasm, the module the compiler built from this file, in your browser. How this works

$ iyi run structs.iyi