ADTs + Match

[jprochazk]

enum Modifier:
  Shift = 0x01
  Ctrl = 0x02
  Alt = 0x04

enum Event:
  Click:
    x: int
    y: int
  MouseMove:
    dx: int
    dy: int
  KeyPress:
    mod: Modifier
    code: int

match v:
  case "a": pass
  case "b" | "c": pass

match response.status:
  case 100..=199: print "info"
  case 200..=299: print "success"
  case 300..=399: print "redirect"
  case 400..=499: print "client error"
  case 500..: print "server error"

match v:
  case true: pass
  case false: pass

match v:
  case _: pass

fn first(list):
  match items:
    case [v]:
      return v
  return none

fn last(list):
  match items:
    case [*, v]:
      return v
  return none

fn middle(list):
  match items:
    case [_, *v, _]:
      return v
  return []

print first([3, 4, 5]), first([])
print last([3, 4, 5]), last([])
print middle([3, 4, 5, 6]), middle([3, 6])

for action in actions:
  match action:
    case {text: message, color: c}:
      ui.set_text_color(c)
      ui.display(message)
    case {sleep: duration}:
      ui.wait(duration)
    case {sound: url, format: "ogg"}:
      ui.play(url)
    case {sound: _, format: _}:
      warning("Unsupported audio format")

match Test(a=0, b=1):
  case Test(a=0..=10, b=1..=5):
    print a, b
  case _:
    print "?"

match event():
  case Event.Click(x, y):
    print "click", x, y
  case e:
    print "unhandled event", e

class A: ...
   
enum Test:
  A:
    a: A
  B:
   x: int
   y: int

match Test.A(a=A(5)):
  case Test.A(a=A(x)): ...
  case Test.B(x, y): ...

# vs
enum Test:
  A(A)
  B: 
    x: int
    y: int

match Test.A(A(5)):
  case Test.A(A(x)): ...
  case Test.B(x, y): ...