6b5edc77b4
The cursor clause now matches the collection form's ': (capture)' — 'for 0..N: (i)' instead of 'for 0..N (i)'. The colon is required when a cursor is present; the no-cursor form 'for 0..N { }' is unchanged. Updated examples/200, the pack-index doc comment, and the spec.
40 lines
1.2 KiB
Plaintext
40 lines
1.2 KiB
Plaintext
// Range-based for loops: `for start..end: (i) { }` (cursor optional, `end`
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// exclusive) is a runtime counting loop; `inline for start..end: (i) { }`
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// is comptime-unrolled — the cursor is a compile-time constant each
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// iteration, so `xs[i]` over a heterogeneous pack substitutes the concrete
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// per-position element (this is what drives pack iteration).
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#import "modules/std.sx";
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Show :: protocol {
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show :: () -> string;
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}
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A :: struct { x: s64; }
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B :: struct { s: string; }
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impl Show for A { show :: (self: *A) -> string => "A"; }
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impl Show for B { show :: (self: *B) -> string => "B"; }
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// Comptime-unrolled iteration over a pack; cursor `i` indexes the pack.
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each :: (..xs: Show) -> void {
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inline for 0..xs.len: (i) {
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print("[{}]={}\n", i, xs[i].show());
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}
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}
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main :: () -> s32 {
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// Runtime range, cursor used.
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for 0..3: (i) { print("i={}\n", i); }
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// Runtime range, no cursor — body runs `end - start` times.
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n := 0;
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for 0..5 { n = n + 1; }
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print("n={}\n", n);
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// Non-zero start.
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for 2..5: (j) { print("j={}\n", j); }
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// Inline unroll over a heterogeneous pack.
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each(A.{ x = 1 }, B.{ s = "hi" }, A.{ x = 3 });
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0;
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}
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