Types¶
Value Types¶
\[\begin{split}\begin{array}{llcll@{\qquad\qquad}l}
\def\mathdef2425#1{{}}\mathdef2425{value type} & \href{../text/types.html#text-valtype}{\mathtt{valtype}} &::=&
\def\mathdef2462#1{\mbox{‘}\mathtt{#1}\mbox{’}}\mathdef2462{i32} &\Rightarrow& \href{../syntax/types.html#syntax-valtype}{\mathsf{i32}} \\ &&|&
\def\mathdef2463#1{\mbox{‘}\mathtt{#1}\mbox{’}}\mathdef2463{i64} &\Rightarrow& \href{../syntax/types.html#syntax-valtype}{\mathsf{i64}} \\ &&|&
\def\mathdef2464#1{\mbox{‘}\mathtt{#1}\mbox{’}}\mathdef2464{f32} &\Rightarrow& \href{../syntax/types.html#syntax-valtype}{\mathsf{f32}} \\ &&|&
\def\mathdef2465#1{\mbox{‘}\mathtt{#1}\mbox{’}}\mathdef2465{f64} &\Rightarrow& \href{../syntax/types.html#syntax-valtype}{\mathsf{f64}} \\
\end{array}\end{split}\]
Function Types¶
\[\begin{split}\begin{array}{llclll@{\qquad\qquad}l}
\def\mathdef2425#1{{}}\mathdef2425{function type} & \href{../text/types.html#text-functype}{\mathtt{functype}} &::=&
\def\mathdef2466#1{\mbox{‘}\mathtt{#1}\mbox{’}}\mathdef2466{(}~\def\mathdef2467#1{\mbox{‘}\mathtt{#1}\mbox{’}}\mathdef2467{func}~~t_1^\ast{:\,}\href{../text/conventions.html#text-vec}{\mathtt{vec}}(\href{../text/types.html#text-functype}{\mathtt{param}})~~t_2^\ast{:\,}\href{../text/conventions.html#text-vec}{\mathtt{vec}}(\href{../text/types.html#text-functype}{\mathtt{result}})~\def\mathdef2468#1{\mbox{‘}\mathtt{#1}\mbox{’}}\mathdef2468{)}
&\Rightarrow& [t_1^\ast] \href{../syntax/types.html#syntax-functype}{\rightarrow} [t_2^\ast] \\
\def\mathdef2425#1{{}}\mathdef2425{parameter} & \href{../text/types.html#text-functype}{\mathtt{param}} &::=&
\def\mathdef2469#1{\mbox{‘}\mathtt{#1}\mbox{’}}\mathdef2469{(}~\def\mathdef2470#1{\mbox{‘}\mathtt{#1}\mbox{’}}\mathdef2470{param}~~\href{../text/values.html#text-id}{\mathtt{id}}^?~~t{:}\href{../text/types.html#text-valtype}{\mathtt{valtype}}~\def\mathdef2471#1{\mbox{‘}\mathtt{#1}\mbox{’}}\mathdef2471{)}
&\Rightarrow& t \\
\def\mathdef2425#1{{}}\mathdef2425{result} & \href{../text/types.html#text-functype}{\mathtt{result}} &::=&
\def\mathdef2472#1{\mbox{‘}\mathtt{#1}\mbox{’}}\mathdef2472{(}~\def\mathdef2473#1{\mbox{‘}\mathtt{#1}\mbox{’}}\mathdef2473{result}~~t{:}\href{../text/types.html#text-valtype}{\mathtt{valtype}}~\def\mathdef2474#1{\mbox{‘}\mathtt{#1}\mbox{’}}\mathdef2474{)}
&\Rightarrow& t \\
\end{array}\end{split}\]
Abbreviations¶
Multiple anonymous parameters or results may be combined into a single declaration:
\[\begin{split}\begin{array}{llclll}
\def\mathdef2425#1{{}}\mathdef2425{parameter} &
\def\mathdef2475#1{\mbox{‘}\mathtt{#1}\mbox{’}}\mathdef2475{(}~~\def\mathdef2476#1{\mbox{‘}\mathtt{#1}\mbox{’}}\mathdef2476{param}~~\href{../text/types.html#text-valtype}{\mathtt{valtype}}^\ast~~\def\mathdef2477#1{\mbox{‘}\mathtt{#1}\mbox{’}}\mathdef2477{)} &\equiv&
(\def\mathdef2478#1{\mbox{‘}\mathtt{#1}\mbox{’}}\mathdef2478{(}~~\def\mathdef2479#1{\mbox{‘}\mathtt{#1}\mbox{’}}\mathdef2479{param}~~\href{../text/types.html#text-valtype}{\mathtt{valtype}}~~\def\mathdef2480#1{\mbox{‘}\mathtt{#1}\mbox{’}}\mathdef2480{)})^\ast \\
\def\mathdef2425#1{{}}\mathdef2425{result} &
\def\mathdef2481#1{\mbox{‘}\mathtt{#1}\mbox{’}}\mathdef2481{(}~~\def\mathdef2482#1{\mbox{‘}\mathtt{#1}\mbox{’}}\mathdef2482{result}~~\href{../text/types.html#text-valtype}{\mathtt{valtype}}^\ast~~\def\mathdef2483#1{\mbox{‘}\mathtt{#1}\mbox{’}}\mathdef2483{)} &\equiv&
(\def\mathdef2484#1{\mbox{‘}\mathtt{#1}\mbox{’}}\mathdef2484{(}~~\def\mathdef2485#1{\mbox{‘}\mathtt{#1}\mbox{’}}\mathdef2485{result}~~\href{../text/types.html#text-valtype}{\mathtt{valtype}}~~\def\mathdef2486#1{\mbox{‘}\mathtt{#1}\mbox{’}}\mathdef2486{)})^\ast \\
\end{array}\end{split}\]
Limits¶
\[\begin{split}\begin{array}{llclll}
\def\mathdef2425#1{{}}\mathdef2425{limits} & \href{../text/types.html#text-limits}{\mathtt{limits}} &::=&
n{:}\href{../text/values.html#text-int}{\def\mathdef2450#1{{\mathtt{u}#1}}\mathdef2450{\mathtt{32}}} &\Rightarrow& \{ \href{../syntax/types.html#syntax-limits}{\mathsf{min}}~n, \href{../syntax/types.html#syntax-limits}{\mathsf{max}}~\epsilon \} \\ &&|&
n{:}\href{../text/values.html#text-int}{\def\mathdef2450#1{{\mathtt{u}#1}}\mathdef2450{\mathtt{32}}}~~m{:}\href{../text/values.html#text-int}{\def\mathdef2450#1{{\mathtt{u}#1}}\mathdef2450{\mathtt{32}}} &\Rightarrow& \{ \href{../syntax/types.html#syntax-limits}{\mathsf{min}}~n, \href{../syntax/types.html#syntax-limits}{\mathsf{max}}~m \} \\
\end{array}\end{split}\]
Memory Types¶
\[\begin{split}\begin{array}{llclll@{\qquad\qquad}l}
\def\mathdef2425#1{{}}\mathdef2425{memory type} & \href{../text/types.html#text-memtype}{\mathtt{memtype}} &::=&
\mathit{lim}{:}\href{../text/types.html#text-limits}{\mathtt{limits}} &\Rightarrow& \mathit{lim} \\
\end{array}\end{split}\]
Table Types¶
\[\begin{split}\begin{array}{llclll}
\def\mathdef2425#1{{}}\mathdef2425{table type} & \href{../text/types.html#text-tabletype}{\mathtt{tabletype}} &::=&
\mathit{lim}{:}\href{../text/types.html#text-limits}{\mathtt{limits}}~~\mathit{et}{:}\href{../text/types.html#text-elemtype}{\mathtt{elemtype}} &\Rightarrow& \mathit{lim}~\mathit{et} \\
\def\mathdef2425#1{{}}\mathdef2425{element type} & \href{../text/types.html#text-elemtype}{\mathtt{elemtype}} &::=&
\def\mathdef2487#1{\mbox{‘}\mathtt{#1}\mbox{’}}\mathdef2487{funcref} &\Rightarrow& \href{../syntax/types.html#syntax-elemtype}{\mathsf{funcref}} \\
\end{array}\end{split}\]
Note
Additional element types may be introduced in future versions of WebAssembly.
Global Types¶
\[\begin{split}\begin{array}{llclll}
\def\mathdef2425#1{{}}\mathdef2425{global type} & \href{../text/types.html#text-globaltype}{\mathtt{globaltype}} &::=&
t{:}\href{../text/types.html#text-valtype}{\mathtt{valtype}} &\Rightarrow& \href{../syntax/types.html#syntax-mut}{\mathsf{const}}~t \\ &&|&
\def\mathdef2488#1{\mbox{‘}\mathtt{#1}\mbox{’}}\mathdef2488{(}~\def\mathdef2489#1{\mbox{‘}\mathtt{#1}\mbox{’}}\mathdef2489{mut}~~t{:}\href{../text/types.html#text-valtype}{\mathtt{valtype}}~\def\mathdef2490#1{\mbox{‘}\mathtt{#1}\mbox{’}}\mathdef2490{)} &\Rightarrow& \href{../syntax/types.html#syntax-mut}{\mathsf{var}}~t \\
\end{array}\end{split}\]