Result Handling Cookbook

This subsection is the canonical v0.33.6 guide for Nitpick's Result<T> handling surface. It supersedes older scattered notes in guide/types/result.md, guide/functions/result_system.md, and guide/operators/result_operators.md where those pages disagree with the v0.33.x audits.

The v0.33.x cycle locked the shipped behavior of every Result-family operator and keyword: pass, fail, ?, ??, ?!, ?|, defaults, drop, raw, _?, _!, safe navigation, and contextual catch.

Chapters

1. Cheatsheet — one-page table for every Result, Optional/null, shorthand, and contextual handler surface.
2. Pass and fail — implicit Result<T> returns, pass, fail, Result<NIL>, and nested call frames.
3. ? fallback unwrap — expr ? fallback, nested explicit fallback, and await parser shape.
4. ?? and ?. — Optional/pointer null coalescing and safe navigation; not Result error handling.
5. defaults and ?| — scoped fallback for expression chains and the primary-expression fallback rule.
6. ?! emphatic fallback — Result-only fallback unwrap with emphatic spelling; no source-level failsafe dispatch.
7. raw, drop, _!, _? — explicit unwrap/discard surfaces and shorthand operand-shape details.
8. Contextual catch — result catch (err) { handler }, error binding scope, and identifier compatibility.
9. Diagnostics and validation — common errors, decision IDs, bug fixtures, K coverage, and v0.33.6 counters.

Quick mental model

• Use pass value and fail code inside ordinary functions.
• Use expr ? fallback when you have an explicit fallback value.
• Use expr defaults fallback or expr ?| fallback when a whole expression chain should fall back together.
• Use expr catch (err) { handler } when the fallback needs the error code.
• Use raw expr / _! expr only when you intentionally ignore failure state.
• Use drop expr / _? expr when you intentionally discard the result.
• Use ?? and ?. for Optional/pointer/null shapes, not Result errors.

Validation snapshot (v0.33.6)

• Compiler CTest: 152/152 for the non-K-wrapper sweep at v0.33.5.
• K core tests: 192/192.
• K proofs: 13/13.
• Result bug regressions: bug646–bug674.
• catch remains contextual, not a hard keyword.