Recipes

One page per topic, one short example per thing you might want. Each is a declaration, a document, and what the library printed for it. Nothing else: when you are looking up “how do I do X” you should not have to read a paragraph first.

The guides are where the reasoning lives. Come here when you want the shape and want it now.

The map

Shapes	Nested types, arrays, dictionaries, integer widths, bytes, inlining
Presence	Required, optional, default, salvaged, ignored, null versus absent
Names	Key styles, renaming, aliases, paths, extras, unknown keys
Rules	Every validator, custom messages, normalising, coercion
Checks and transforms	Your own logic, cross-field, changing the type
Dates	Formats, candidate chains, date rules
Enums	Closed, open, one-or-many, wrapping a scalar
Unions	Tagged and untagged
Encoding	Writing all four formats, round-trip, JSON Schema
Unknown shapes	Value models, and schemas with no declaration

Then, when what you have is a whole job rather than one feature:

A JSON API endpoint	Negotiation, rules, problem details, status codes
An application config file	Defaults, typos, carets at boot
An API that keeps changing	Aliases, fallbacks, open enums, extras
A form with errors on the fields	Paths to field names, your own wording
A file you do not trust	Limits, and what each one stops

Everything here ran

Every example on these pages is a real program in this site’s build: it compiles against the package, runs, and the page shows what it printed. Nothing is illustrative.

That is not only a promise about accuracy. It has found four bugs so far. A handler answering 415 with a body claiming 422. A documented path that did not work. A caret that went missing on four formats. An example in the guides that would not compile.

Examples that have to run are a test suite with a readership.