sx/examples/0118-types-type-all-interactions.sx

// Type as a first-class value — comprehensive interaction smoke.
//
// Every way a user can plausibly touch a `Type` value, in one
// place. Pre-fix: some sections fail (`<?>`, false, garbage, or
// compile errors). Post-fix: every section's output matches the
// header line.
//
// Sections labelled `--- N. <thing> ---` so the diff localises
// which interaction regressed.

#import "modules/std.sx";

// ── Test fixtures ─────────────────────────────────────────────

Point :: struct { x: i32; y: i32; }

Color :: enum { red; green; blue; }

Wrap :: struct ($T: Type) { v: T; }

identity :: ($T: Type, val: T) -> T => val;

// Generic comptime fn that dispatches on type identity (compile-
// time fold via type_eq → const_bool → inline-if folds the
// branch away).
describe :: ($T: Type) -> string {
    inline if type_eq(T, i64) { return "int64"; }
    inline if type_eq(T, string) { return "text"; }
    inline if type_eq(T, bool) { return "boolean"; }
    return "other";
}

// Pack-fn collecting per-position types (step 4A.bare path).
type_list :: (..$args) -> string {
    list := $args;
    s := "[";
    i : i64 = 0;
    while i < list.len {
        if i > 0 { s = concat(s, ", "); }
        s = concat(s, type_name(list[i]));
        i = i + 1;
    }
    return concat(s, "]");
}

// Type stored in a struct field.
TypeHolder :: struct { t: Type; }

main :: () -> i32 {
    // ── 1. Type literal equality ────────────────────────────
    print("=== 1. literal == ===\n");
    print("i64 == i64:    {}\n", i64 == i64);
    print("i64 == string: {}\n", i64 == string);
    print("*u8 == *u8:    {}\n", *u8 == *u8);
    print("?i64 == ?i64:  {}\n", ?i64 == ?i64);
    print("?i64 == ?i32:  {}\n", ?i64 == ?i32);

    // ── 2. type_of(value) ───────────────────────────────────
    print("=== 2. type_of(value) == T ===\n");
    a : i64 = 42;
    b : f64 = 3.14;
    s : string = "hi";
    print("type_of(a) == i64:    {}\n", type_of(a) == i64);
    print("type_of(b) == f64:    {}\n", type_of(b) == f64);
    print("type_of(s) == string: {}\n", type_of(s) == string);
    print("type_of(a) == f64:    {}\n", type_of(a) == f64);

    // ── 3. Type variable storage + readback ─────────────────
    print("=== 3. Type variable storage ===\n");
    t : Type = f64;
    print("t == f64:    {}\n", t == f64);
    print("t == string: {}\n", t == string);
    t = string;
    print("after reassign t == string: {}\n", t == string);
    t = bool;
    print("t == bool:   {}\n", t == bool);

    // ── 4. type_name on literals + variables ────────────────
    print("=== 4. type_name ===\n");
    print("type_name(i64):    {}\n", type_name(i64));
    print("type_name(*u8):    {}\n", type_name(*u8));
    print("type_name(Point):  {}\n", type_name(Point));
    print("type_name(Color):  {}\n", type_name(Color));
    t = f64;
    print("type_name(t):      {}\n", type_name(t));

    // ── 5. Print Type values directly ───────────────────────
    print("=== 5. print Type values ===\n");
    print("literal: {}\n", i64);
    t = string;
    print("var:     {}\n", t);
    print("type_of(b): {}\n", type_of(b));

    // ── 6. Generic dispatch via $T: Type ────────────────────
    print("=== 6. generic dispatch ===\n");
    print("describe(i64):    {}\n", describe(i64));
    print("describe(string): {}\n", describe(string));
    print("describe(bool):   {}\n", describe(bool));
    print("describe(f64):    {}\n", describe(f64));

    // ── 7. identity(T, val) ─────────────────────────────────
    print("=== 7. identity($T, val) ===\n");
    print("identity(i64, 7):     {}\n", identity(i64, 7));
    print("identity(string, hi): {}\n", identity(string, "hi"));
    print("identity(bool, true): {}\n", identity(bool, true));

    // ── 8. Comptime-generated struct (Wrap($T)) ─────────────
    print("=== 8. Wrap($T) ===\n");
    w_int := Wrap(i64).{ v = 42 };
    w_str := Wrap(string).{ v = "wrapped" };
    print("Wrap(i64).v:    {}\n", w_int.v);
    print("Wrap(string).v: {}\n", w_str.v);

    // ── 9. Reflection builtins on Types ─────────────────────
    print("=== 9. reflection on Type ===\n");
    print("size_of(i64):      {}\n", size_of(i64));
    print("size_of(*u8):      {}\n", size_of(*u8));
    print("align_of(f64):     {}\n", align_of(f64));
    print("field_count(Point): {}\n", field_count(Point));
    print("type_eq(i64, i64):    {}\n", type_eq(i64, i64));
    print("type_eq(i64, string): {}\n", type_eq(i64, string));

    // ── 10. Type pack (..$args) walking ─────────────────────
    print("=== 10. ..$args walking ===\n");
    print("type_list():            {}\n", type_list());
    print("type_list(1):           {}\n", type_list(42));
    print("type_list(1, \"x\"):    {}\n", type_list(42, "x"));
    print("type_list(true, 3.14):  {}\n", type_list(true, 3.14));

    // ── 11. Type in struct field ────────────────────────────
    print("=== 11. Type in struct field ===\n");
    h := TypeHolder.{ t = i64 };
    print("h.t == i64:    {}\n", h.t == i64);
    print("h.t == string: {}\n", h.t == string);
    print("type_name(h.t): {}\n", type_name(h.t));

    // ── 12. Compound type literals ──────────────────────────
    print("=== 12. compound literals ===\n");
    print("type_name(*Point):    {}\n", type_name(*Point));
    print("type_name([4]i32):    {}\n", type_name([4]i32));
    print("type_name([]bool):    {}\n", type_name([]bool));
    print("type_name(?f64):      {}\n", type_name(?f64));

    return 0;
}

// ** stdout **
// === 1. literal == ===
// i64 == i64:    true
// i64 == string: false
// *u8 == *u8:    true
// ?i64 == ?i64:  true
// ?i64 == ?i32:  false
// === 2. type_of(value) == T ===
// type_of(a) == i64:    true
// type_of(b) == f64:    true
// type_of(s) == string: true
// type_of(a) == f64:    false
// === 3. Type variable storage ===
// t == f64:    true
// t == string: false
// after reassign t == string: true
// t == bool:   true
// === 4. type_name ===
// type_name(i64):    i64
// type_name(*u8):    *u8
// type_name(Point):  Point
// type_name(Color):  Color
// type_name(t):      f64
// === 5. print Type values ===
// literal: i64
// var:     string
// type_of(b): f64
// === 6. generic dispatch ===
// describe(i64):    int64
// describe(string): text
// describe(bool):   boolean
// describe(f64):    other
// === 7. identity($T, val) ===
// identity(i64, 7):     7
// identity(string, hi): hi
// identity(bool, true): true
// === 8. Wrap($T) ===
// Wrap(i64).v:    42
// Wrap(string).v: wrapped
// === 9. reflection on Type ===
// size_of(i64):      8
// size_of(*u8):      8
// align_of(f64):     8
// field_count(Point): 2
// type_eq(i64, i64):    true
// type_eq(i64, string): false
// === 10. ..$args walking ===
// type_list():            []
// type_list(1):           [i64]
// type_list(1, "x"):      [i64, string]
// type_list(true, 3.14):  [bool, f64]
// === 11. Type in struct field ===
// h.t == i64:    true
// h.t == string: false
// type_name(h.t): i64
// === 12. compound literals ===
// type_name(*Point):    *Point
// type_name([4]i32):    [4]i32
// type_name([]bool):    []bool
// type_name(?f64):      ?f64