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sx/examples/errors/1009-errors-catch.sx
agra 66bdc70bf1 test: group examples into per-category folders
Move examples/*.sx and their expected/ snapshots into per-category
subfolders (examples/<category>/...). Folder = leading filename token,
with ffi-objc/ffi-jni kept whole; filenames are unchanged. The corpus
runner and LSP sweep now discover each category's expected/ dir, while
issues/ stays flat. Example 1058's repo-root-relative companion import
is made file-relative. Path strings embedded in 164 snapshots were
regenerated (path-only changes). Test-layout docs in CLAUDE.md updated.
2026-06-21 14:41:34 +03:00

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// `catch` on a pure-failable LHS (ERR step E1.5). `expr catch [e] BODY`
// consumes the error inline: on failure it binds the tag to `e` (optional)
// and runs BODY; on success the result is void (a `-> !` LHS has no success
// value). BODY may diverge (`return` / `raise` — typed `noreturn`, E1.4c) or
// fall through. `catch` needs no failable *enclosing* function — it handles
// the error locally. All four body forms appear below: block, no-binding
// block, match-body (`== { case ... }`), and the selective handle + re-raise
// pattern. Value-carrying `-> (T, !)` catch (binding the success value) lands
// with the tuple ABI in E2.
#import "modules/std.sx";
E :: error { Bad, Empty }
must :: (n: i32) -> !E {
if n < 0 { raise error.Bad; }
if n == 0 { raise error.Empty; }
return;
}
// Diverging body — returns from `classify` on error.
classify :: (n: i32) -> i32 {
must(n) catch (e) {
if e == error.Bad { return 1; }
if e == error.Empty { return 2; }
return 9;
};
return 0; // must(n) succeeded
}
// Match-body form — sugar for `catch (e) { if e == { case ... } }`.
mclassify :: (n: i32) -> i32 {
must(n) catch (e) == {
case .Bad: return 11;
case .Empty: return 22;
else: return 99;
};
return 0;
}
// Selective handle + re-raise (failable enclosing fn; `raise e` is the
// variable form). Swallows Bad → success; re-raises everything else.
handle_some :: (n: i32) -> !E {
must(n) catch (e) {
if e == error.Bad { return; } // swallow → success
raise e; // re-raise the rest
};
return;
}
main :: () -> i32 {
r : i32 = 0;
must(-1) catch (e) { if e == error.Bad { r = r + 1; } }; // Bad → +1
must(5) catch { r = r + 100; }; // success → body skipped
r = r + classify(0); // Empty → 2
r = r + classify(8); // success → 0
he := handle_some(0); // Empty re-raised
if he == error.Empty { r = r + 4; } // +4
hb := handle_some(-1); // Bad swallowed → success
if hb == error.Bad { r = r + 50; } // not taken
r = r + mclassify(-1); // Bad → 11
print("catch result: {}\n", r); // 1+2+4+11 = 18
return r;
}