JSON and YAML

Parsing

let summary: Summary! = fromJSON("""{"name": "test", "count": 42}""")
let status: Status! = fromJSON("\"PASSED\"")
let cfg = fromYAML("name: foo\ncount: 1")

• parsing is type-driven: the expected type guides decoding. The type comes from a :: cast (Types and nullability), an annotation, or the parameter/return type at the call site (fromJSON(...) :: Status!, let x: Summary! = fromJSON(...), pub f(d: String!): Summary! { fromJSON(d) })
• works for primitives, lists, records, custom types (Objects (type)), enums (Enums and scalars)
• unknown/extra fields in the input are ignored, not errors
• fromJSON rejects trailing data after the first value

Serialization

• toJSON(value) — String!; object/record keys are emitted in alphabetical order (see Literals)
• toString(value) — pass-through for strings, JSON-encode otherwise (see Strings)

Coercion during parsing

• enum values decode from their string names ("PASSED" / PASSED → Status.PASSED)
• custom scalars decode from their string forms
• record/object fields fall back to declared defaults when absent (withDefault: String! = "default")
• nullable fields absent from input decode to null

Common errors

• invalid JSON / YAML → raises (invalid JSON: ... / invalid YAML: ...)
• missing required field → raises (<path>: missing required field)
• wrong type for field → raises
• invalid enum value → raises (<path>: invalid enum value "X" for <Enum>)

All of these are catchable with try/catch (Errors: try, catch, raise).