@require: option
@require: class-slydifi/theme/akasaka
@require: code-printer/code-design
@require: code-printer/code-printer
@require: code-printer/code-syntax
@require: code-printer/code-theme
@require: figbox/figbox

let-block +code-block-php source =
  '<
    +code-printer?:(
      CodePrinter.make-config CodeSyntax.php CodeTheme.iceberg-light
      |> CodePrinter.set-number-fun CodeDesign.number-fun-null
    )(source);
  >

let big-textbox ?:size-opt it =
  let size = Option.from 32pt size-opt in
    FigBox.textbox?:(set-font-size size) it

open FigBox
in

document '<
  +set-config(|
    SlydifiThemeAkasaka.default-config with
    color-emph = Color.black;
  |);

  +make-title(|
    title = {
      |PHPStanの力で
      |Algebraic Data Typesを
      |実現する
      |};
    author = {|nsfisis (いまむら)|};
    date = {|第160回PHP勉強会＠東京|};
  |);

  %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

  +frame{自己紹介}<
    +fig-center(vconcat [
      gap 75pt;
      hconcat [
        big-textbox{nsfisis (いまむら)};
        gap 20pt;
        include-image 50pt `assets/me.jpeg`;
      ];
      gap 20pt;
      big-textbox{\@ デジタルサーカス株式会社};
    ]);
  >

  %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

  +frame{ADTとは}<
    +fig-center(vconcat [
      gap 75pt;
      big-textbox?:(48pt){Algebraic Data Type};
      gap 20pt;
      big-textbox?:(48pt){代数的データ型};
    ]);
  >

  +frame{ADTとは}<
    +fig-center(vconcat [
      gap 75pt;
      big-textbox?:(48pt){すごい enum 型};
    ]);
  >

  +frame{ADTの例}<
    +code-block-php(`// 注: これは架空の文法です
enum JsonValue {
    case Null;
    case Boolean(bool);
    case Number(int|float);
    case String(string);
    case Array(array);
    case Object(array);
}
`);
  >

  +frame{ADTの例(今回扱うもの)}<
    +code-block-php(`// 注: これは架空の文法です
enum OptionalInt {
    case None;
    case Some(int);
}
`);
  >

  +frame{実現したいもの}<
    +code-block-php(`// OptionalInt を返す関数
function f() { /* 略 */ }

$x = f();
if (/* $x が値を持っているかどうか判定する */) {
    echo /* $x が内部に持っている int の値を「安全に」取り出す */;
}
`);
  >

  +frame{どうやって実現するか？}<
    +fig-center(vconcat [
      gap 40pt;
      big-textbox{Array shape 編};
      gap 20pt;
      big-textbox{Object shape 編};
      gap 20pt;
      big-textbox{Type assertion 編};
      gap 20pt;
      big-textbox{PHPStan 魔改造編};
    ]);
  >

  %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

  +section{|Array shape 編|}<
  +frame{Array shape}<
    +code-block-php(`$none = [
    'has_value' => false,
];
$some = [
    'has_value' => true,
    'value' => 42,
];`);
  >

  +frame{Array shape}<
    +code-block-php(`/** @var array{has_value: false} $none */
$none = [
    'has_value' => false,
];
/** @var array{has_value: true, value: int} $some */
$some = [
    'has_value' => true,
    'value' => 42,
];`);
  >

  +frame{Array shape}<
    +code-block-php(`/** @return (array{has_value: false}
             |array{has_value: true, value: int}) */
function f(): array { /* 略 */ }`);
  >

  +frame{Array shape}<
    +code-block-php(`/** @return (array{has_value: false}
             |array{has_value: true, value: int}) */
function f(): array { /* 略 */ }

$x = f();
if ($x['has_value']) {
    // PHPStan は、$x['value'] が int であることを認識できる
    echo $x['value'];
}
`);
  >
  >

  %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

  +section{|Object shape 編|}<
  +frame{Object shape}<
    +code-block-php(`/** @var object{has_value: false} $none */
$none = (object)[
    'has_value' => false,
];
/** @var object{has_value: true, value: int} $some */
$some = (object)[
    'has_value' => true,
    'value' => 42,
];`);
  >

  +frame{Object shape}<
    +code-block-php(`/** @return (object{has_value: false}
             |object{has_value: true, value: int}) */
function f(): stdClass { /* 略 */; }

$x = f();
if ($x->has_value) {
    // 型が絞りこまれない！
    echo $x->value;
}
`);
  >
  >

  %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

  +section{|Type assertion 編|}<
  +frame{Type assertion}<
    +code-block-php(`/** @phpstan-assert-if-true int $a */
/** @phpstan-assert-if-false !int $a */
function check_is_int(mixed $a): bool {
    return is_int($a);
}

$a = hogehoge();
if (check_is_int($a)) {
    PHPStan\dumpType($a);
    // => int
}
`);
  >

  +frame{Type assertion}<
    +code-block-php(`abstract class OptionalInt {
    /**
     * @phpstan-assert-if-true OptionalIntSome $this
     * @phpstan-assert-if-false OptionalIntNone $this
     */
    public function hasValue(): bool {
        return $this instanceof OptionalIntSome;
    }
}
class OptionalIntNone extends OptionalInt {}
class OptionalIntSome extends OptionalInt {
    public function __construct(public int $value) {}
}
`);
  >

  +frame{Type assertion}<
    +code-block-php(`$x = f();
if ($x->hasValue()) {
    echo $x->value;
}
`);
  >

  +frame{Type assertion}<
    +code-block-php(`abstract class OptionalInt {
    /**
     * @phpstan-assert-if-true OptionalIntSome $this
     * @phpstan-assert-if-false OptionalIntNone $this
     */
    public function hasValue(): bool {
        return $this instanceof OptionalIntSome;
    }
}
class OptionalIntNone extends OptionalInt {}
class OptionalIntSome extends OptionalInt {
    public function __construct(public int $value) {}
}
`);
  >
  >

  %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

  +frame{ここまでのまとめ}<
    +fig-center(vconcat [
      gap 40pt;
      big-textbox{Array shape ではうまく動く};
      gap 20pt;
      big-textbox{Object shape では動かない};
      gap 20pt;
      big-textbox{Type assertion では動くが課題アリ};
      gap 40pt;
      big-textbox{Object shape でも型を絞り込みたい！};
    ]);
  >

  +section{|PHPStan 魔改造編|}<
  +frame{PHPStan 魔改造}<
    +code-block-php(`if ($x['has_value']) {
    // $x['has_value'] の型が truthy に確定したことで、
    // $x に HasOffsetValueType('has_value', truthy)
    // という型が付く
    echo $x['value'];
}
`);
  >

  +frame{PHPStan 魔改造}<
    +code-block-php(`if ($x['has_value']) {
    // $x['has_value'] の型が truthy に確定したことで、
    // $x に HasOffsetValueType('has_value', truthy)
    // という型が付く
    echo $x['value'];
}
`);
    +p{}
    +code-block-php(`// (array{has_value: false}
//  |array{has_value: true, value: int})
// と
// HasOffsetValueType('has_value', truthy)
// とを合成する

`#);
  >

  +frame{PHPStan 魔改造}<
    +fig-center(vconcat [
      gap 75pt;
      big-textbox?:(24pt){HasOffsetValueType を付ける};
      gap 20pt;
      big-textbox?:(24pt){HasOffsetValueType と array shape を合成する};
    ]);
  >

  +frame{PHPStan 魔改造}<
    +fig-center(vconcat [
      gap 75pt;
      big-textbox?:(24pt){HasPropertyValueType を付ける};
      gap 20pt;
      big-textbox?:(24pt){HasPropertyValueType と object shape を合成する};
    ]);
  >
  >

  %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

  +frame{まとめ}<
    +fig-center(vconcat [
      gap 75pt;
      big-textbox?:(24pt){PHPStan と array shape を使った ADT もどき};
      gap 20pt;
      big-textbox?:(24pt){Object shape での型の絞り込みは未実装};
      gap 20pt;
      big-textbox?:(24pt){現在鋭意実装中};
    ]);
  >

  +frame{宣伝}<
    +fig-center(vconcat [
      gap 75pt;
      big-textbox{3/7-9: PHPerKaigi 2024};
      gap 20pt;
      big-textbox{3/15-16: Ya8 2024};
      gap 20pt;
      big-textbox{4/13: PHPカンファレンス小田原 2024};
    ]);
  >

>