error

type struct Name { ... }
type enum Name { ... }
type trait Name { ... }
type union Name { ... }

Begins a type declaration; the keyword that follows says which kind. On its own, type Name = Existing; declares an alias.

type struct Name {
    field: Type;
    method(&this) -> Ret { ... }
}

A value type with named fields and optional methods. Structs live on the stack and are passed by value. Fields are public by default and may carry = default values; methods take their receiver as &this, mut &this, or this.

type enum JsonErrorKind {
    UnexpectedEof;
    UnexpectedChar;
    InvalidNumber;
    InvalidEscape;
    InvalidUnicode;
    DepthExceeded;
    TrailingData;
    KeyNotString;
    OutOfMemory;
}

Closed set of failure kinds the JSON parser produces. New kinds are rare; most failures fold into one of these.

JsonError.line: u64

1-indexed line of the offending byte.

primitive u64

64-bit unsigned integer.

JsonError.column: u64

1-indexed column of the offending byte.

JsonError.offset: u64

0-indexed byte offset into the source.

JsonError.msg: String

Human-readable detail. Owned; call drop before discarding.

type struct String<A = GlobalAlloc> {
    buffer: RawBuffer<u8, A>;
    length: u64;
}

String: owned, heap-allocated, length-typed UTF-8.

static name(param: Type) -> Ret { ... }

A method that belongs to the type rather than an instance, called as Type::name(..). For structs, static new(..) returning a struct literal is the idiomatic constructor.

JsonError::describe(&this) -> Str

A short, stable description of what went wrong, as a borrowed Str. The convergent accessor every stdlib error type exposes (describe(&this) -> Str); Display/Debug for JsonError delegate to it.

&this
mut &this
this

The receiver of a method. Its first parameter declares how the method takes it: &this borrows read-only, mut &this borrows exclusively, and this / mut this move the value in and consume it. In the body, this.field reaches the members.

type struct Str {
    bytes: u8*;
    length: u64;
}

Str: a borrowed UTF-8 string slice.

type enum Name {
    Unit,
    Payload(T),
    Named { x: i32 },
}

An algebraic data type. Variants may be bare or carry a tuple or struct payload, and a match on an enum must cover every variant. Name::Variant names a variant; methods are added with implement enum Name { ... }.

type enum JsonErrorKind {
    UnexpectedEof;
    UnexpectedChar;
    InvalidNumber;
    InvalidEscape;
    InvalidUnicode;
    DepthExceeded;
    TrailingData;
    KeyNotString;
    OutOfMemory;
}

Closed set of failure kinds the JSON parser produces. New kinds are rare; most failures fold into one of these.

JsonErrorKind::UnexpectedEof

Reached end of input mid-value.

JsonErrorKind::UnexpectedChar

Encountered a byte that does not begin a valid token.

JsonErrorKind::InvalidNumber

A number literal could not be parsed (overflow, malformed exponent, lone -, leading zeros, etc.).

JsonErrorKind::InvalidEscape

A \X escape inside a string is not one of the recognized escape sequences.

JsonErrorKind::InvalidUnicode

A \uXXXX sequence is malformed or names an unpaired surrogate.

JsonErrorKind::DepthExceeded

Object/array nesting exceeded parser::MAX_DEPTH.

JsonErrorKind::TrailingData

Garbage after the top-level value.

JsonErrorKind::KeyNotString

Object key was not a string.

JsonErrorKind::OutOfMemory

The parser's working buffer allocation failed (only fires on a genuine malloc returning NULL, e.g. under memory pressure).

implement struct Name { ... }
implement trait Trait for Type { ... }
implement u64 { ... }

Adds methods to a type outside its declaration. implement struct T (or enum, or a bare primitive) opens an inherent block; implement trait Tr for T supplies a trait's methods for one type. Resolution is at compile time - no dynamic dispatch.

implement enum Name { ... }

Names the enum an inherent block extends - the only way to give an enum methods.

JsonErrorKind::label(&this) -> string

Short slug for diagnostics. "unexpected_eof", "invalid_number", etc.

primitive string

NUL-terminated raw string (u8*), matching the C ABI. Length-typed text is Str / String.

import a::b;
import a::b::{ X, Y };
import a::b as c;
import a::b::*;

Brings a module, or selected items from it, into scope. One path per declaration: use the brace form for several items, as to alias, and * for everything public (prefer the brace form; wildcards invite name collisions).

namespace std;

std: the Cryo standard library.

namespace std::json;

json: RFC 8259 JSON parser and serializer.

namespace std::json::error;

JsonError: the failure kind for json::parser.

JsonError.msg: String

Human-readable detail. Owned; call drop before discarding.

JsonError.line: u64

1-indexed line of the offending byte.

JsonError.column: u64

1-indexed column of the offending byte.

JsonError.offset: u64

0-indexed byte offset into the source.

JsonError::describe(&this) -> Str

A short, stable description of what went wrong, as a borrowed Str. The convergent accessor every stdlib error type exposes (describe(&this) -> Str); Display/Debug for JsonError delegate to it.

JsonError::drop(mut &this) -> void

via trait Drop

type trait Display {
    fmt<W>(&this, f: mut &Formatter<W>) -> Result<(), FmtError>
    where W: FmtWrite;
}

Display / Debug / Formatter.

JsonErrorKind::label(&this) -> string

Short slug for diagnostics. "unexpected_eof", "invalid_number", etc.

JsonErrorKind::UnexpectedEof

Reached end of input mid-value.

JsonErrorKind::UnexpectedChar

Encountered a byte that does not begin a valid token.

JsonErrorKind::InvalidNumber

A number literal could not be parsed (overflow, malformed exponent, lone -, leading zeros, etc.).

JsonErrorKind::InvalidEscape

A \X escape inside a string is not one of the recognized escape sequences.

JsonErrorKind::InvalidUnicode

A \uXXXX sequence is malformed or names an unpaired surrogate.

JsonErrorKind::DepthExceeded

Object/array nesting exceeded parser::MAX_DEPTH.

JsonErrorKind::TrailingData

Garbage after the top-level value.

JsonErrorKind::KeyNotString

Object key was not a string.

JsonErrorKind::OutOfMemory

The parser's working buffer allocation failed (only fires on a genuine malloc returning NULL, e.g. under memory pressure).

implement trait Trait for Type { ... }

Introduces a trait implementation: the block supplies, for one concrete type, the method bodies the trait requires.

type trait Drop {
    drop(mut &this) -> void;
}

Drop: explicit destructor.

implement trait Trait for Type { ... }

Names the type a trait implementation is for. The block that follows supplies the bodies the trait requires.