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sx/examples/0053-basic-ufcs-opt-in.sx

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// Free-function dot-calls are OPT-IN. Two opt-in spellings:
// name :: ufcs (params) { body } — the fn itself is dot-callable
// name :: ufcs target; — dot-callable (renaming) alias
// A plain fn is callable directly or via `|>` only (see 1166 for the
// rejection). Generic ufcs fns dispatch through normal monomorphization,
// and the plan-side return type binds from the receiver (structured
// params like `[]$T` included).
#import "modules/std.sx";
bump :: (x: s64) -> s64 { x + 1 }
bump2 :: ufcs (x: s64) -> s64 { x + 2 }
bump3 :: ufcs bump;
Counter :: struct { n: s64; }
inc :: ufcs (c: *Counter, by: s64) -> s64 { c.n += by; c.n }
gfirst :: ufcs (xs: []$T) -> T { xs[0] }
main :: () {
f : s64 = 40;
print("marked: {}\n", f.bump2()); // 42
print("alias: {}\n", f.bump3()); // 41
print("direct: {}\n", bump(f)); // 41 — plain fn, direct
print("pipe: {}\n", f |> bump()); // 41 — plain fn, pipe
print("marked-direct: {}\n", bump2(f)); // 42 — marked fn callable directly
c := Counter.{ n = 10 };
print("ptr-recv: {}\n", c.inc(5)); // 15 — auto address-of receiver
arr := .[7, 8, 9];
xs : []s64 = arr;
print("generic-dot: {}\n", xs.gfirst()); // 7
print("generic-direct: {}\n", gfirst(xs)); // 7 — plan types it s64, not a T stub
}