// Block value rule: a block's value is its last statement ONLY when that
// statement is a trailing expression with NO `;`. A trailing `;` discards the
// value, leaving the block void. This makes value-vs-statement explicit and lets
// the compiler reject "forgot to produce a value".
//
//   { … expr }    → value is `expr`
//   { … expr; }   → void (value discarded)
//
// Match arms are exempt: the arm `;` is an arm terminator, so `case .x: expr;`
// still yields `expr` (only an explicit inner braced block follows the rule).

#import "modules/std.sx";

// Implicit return: trailing expression, no `;`.
double :: (n: s32) -> s32 { n * 2 }

// if/else as a value — each branch's last expression has no `;`.
sign :: (n: s32) -> s32 {
    if n < 0 { -1 } else if n > 0 { 1 } else { 0 }
}

// A value-producing block bound to a name.
sum3 :: (a: s32, b: s32, c: s32) -> s32 {
    t := { x := a + b; x + c };   // block value is `x + c`
    t
}

// Match arms keep their `;` (exempt): the arm `;` is an arm terminator, so each
// arm still yields its expression as the match value.
classify :: (n: s32) -> s32 {
    if n == {
        case 0:  100;
        case 1:  10;
        else:    7;
    }
}

main :: () -> s32 {
    total : s32 = 0;
    total = total + double(10);       // 20
    total = total + sign(-7);         // -1
    total = total + sum3(1, 2, 3);    // 6
    total = total + classify(1);      // 10
    print("block-value total: {}\n", total);   // 20 - 1 + 6 + 10 = 35
    total
}