Values

You can use values in your schema to parametrize types, initialize fields, and match patterns. Values can be of two kinds: literals and constructed values.

\[ \begin{align*} value ::= literal \mid constructed\_value \end{align*} \]

Literals

Literals are used to represent concrete values of basic types like integers, floats, strings, and booleans.

\[ \begin{align*} any &::= \text{any single character except a newline} \\ string\_literal &::= \texttt{"}any_{\langle\texttt{"}\mid\texttt{\\}\rangle}\texttt{"} \\ int\_literal &::= [\texttt{+}\mid\texttt{-}] digit \lbrace digit \rbrace \\ unsigned\_int\_literal &::= digit \lbrace digit \rbrace \texttt{u} \\ float\_literal &::= [\texttt{+}\mid\texttt{-}] digit \lbrace digit \rbrace \texttt{.} digit \lbrace digit \rbrace \\ bool\_literal &::= \texttt{true} \mid \texttt{false} \\ literal &::= string\_literal \mid int\_literal \mid unsigned\_int\_literal \mid float\_literal \mid bool\_literal \end{align*} \]

Constructed Values

Constructed values are used to represent values of complex types like messages and enums. They are created using a type constructor and field initializations. Field initialization must initialize all fields of the type in the order they are declared.

Notice that here we use the \(expression\) production. It will be defined in the next chapter.

\[ \begin{align*} constructed\_value &::= constructor\_identifier ~\texttt{\{}~ field\_inits ~\texttt{\}}~ \\ field\_inits &::= \lbrace field\_init \lbrace ~\texttt{,}~ field\_init \rbrace \rbrace \\ field\_init &::= var\_identifier ~\texttt{:}~ expression \end{align*} \]