Types¶
Value Types¶
\[\begin{split}\begin{array}{llcll@{\qquad\qquad}l}
\def\mathdef2553#1{{}}\mathdef2553{value type} & \href{../text/types.html#text-valtype}{\mathtt{valtype}} &::=&
\def\mathdef2590#1{\mbox{‘}\mathtt{#1}\mbox{’}}\mathdef2590{i32} &\Rightarrow& \href{../syntax/types.html#syntax-valtype}{\mathsf{i32}} \\ &&|&
\def\mathdef2591#1{\mbox{‘}\mathtt{#1}\mbox{’}}\mathdef2591{i64} &\Rightarrow& \href{../syntax/types.html#syntax-valtype}{\mathsf{i64}} \\ &&|&
\def\mathdef2592#1{\mbox{‘}\mathtt{#1}\mbox{’}}\mathdef2592{f32} &\Rightarrow& \href{../syntax/types.html#syntax-valtype}{\mathsf{f32}} \\ &&|&
\def\mathdef2593#1{\mbox{‘}\mathtt{#1}\mbox{’}}\mathdef2593{f64} &\Rightarrow& \href{../syntax/types.html#syntax-valtype}{\mathsf{f64}} \\
\end{array}\end{split}\]
Function Types¶
\[\begin{split}\begin{array}{llclll@{\qquad\qquad}l}
\def\mathdef2553#1{{}}\mathdef2553{function type} & \href{../text/types.html#text-functype}{\mathtt{functype}} &::=&
\def\mathdef2594#1{\mbox{‘}\mathtt{#1}\mbox{’}}\mathdef2594{(}~\def\mathdef2595#1{\mbox{‘}\mathtt{#1}\mbox{’}}\mathdef2595{func}~~t_1^\ast{:\,}\href{../text/conventions.html#text-vec}{\mathtt{vec}}(\href{../text/types.html#text-functype}{\mathtt{param}})~~t_2^\ast{:\,}\href{../text/conventions.html#text-vec}{\mathtt{vec}}(\href{../text/types.html#text-functype}{\mathtt{result}})~\def\mathdef2596#1{\mbox{‘}\mathtt{#1}\mbox{’}}\mathdef2596{)}
&\Rightarrow& [t_1^\ast] \href{../syntax/types.html#syntax-functype}{\rightarrow} [t_2^\ast] \\
\def\mathdef2553#1{{}}\mathdef2553{parameter} & \href{../text/types.html#text-functype}{\mathtt{param}} &::=&
\def\mathdef2597#1{\mbox{‘}\mathtt{#1}\mbox{’}}\mathdef2597{(}~\def\mathdef2598#1{\mbox{‘}\mathtt{#1}\mbox{’}}\mathdef2598{param}~~\href{../text/values.html#text-id}{\mathtt{id}}^?~~t{:}\href{../text/types.html#text-valtype}{\mathtt{valtype}}~\def\mathdef2599#1{\mbox{‘}\mathtt{#1}\mbox{’}}\mathdef2599{)}
&\Rightarrow& t \\
\def\mathdef2553#1{{}}\mathdef2553{result} & \href{../text/types.html#text-functype}{\mathtt{result}} &::=&
\def\mathdef2600#1{\mbox{‘}\mathtt{#1}\mbox{’}}\mathdef2600{(}~\def\mathdef2601#1{\mbox{‘}\mathtt{#1}\mbox{’}}\mathdef2601{result}~~t{:}\href{../text/types.html#text-valtype}{\mathtt{valtype}}~\def\mathdef2602#1{\mbox{‘}\mathtt{#1}\mbox{’}}\mathdef2602{)}
&\Rightarrow& t \\
\end{array}\end{split}\]
Abbreviations¶
Multiple anonymous parameters or results may be combined into a single declaration:
\[\begin{split}\begin{array}{llclll}
\def\mathdef2553#1{{}}\mathdef2553{parameter} &
\def\mathdef2603#1{\mbox{‘}\mathtt{#1}\mbox{’}}\mathdef2603{(}~~\def\mathdef2604#1{\mbox{‘}\mathtt{#1}\mbox{’}}\mathdef2604{param}~~\href{../text/types.html#text-valtype}{\mathtt{valtype}}^\ast~~\def\mathdef2605#1{\mbox{‘}\mathtt{#1}\mbox{’}}\mathdef2605{)} &\equiv&
(\def\mathdef2606#1{\mbox{‘}\mathtt{#1}\mbox{’}}\mathdef2606{(}~~\def\mathdef2607#1{\mbox{‘}\mathtt{#1}\mbox{’}}\mathdef2607{param}~~\href{../text/types.html#text-valtype}{\mathtt{valtype}}~~\def\mathdef2608#1{\mbox{‘}\mathtt{#1}\mbox{’}}\mathdef2608{)})^\ast \\
\def\mathdef2553#1{{}}\mathdef2553{result} &
\def\mathdef2609#1{\mbox{‘}\mathtt{#1}\mbox{’}}\mathdef2609{(}~~\def\mathdef2610#1{\mbox{‘}\mathtt{#1}\mbox{’}}\mathdef2610{result}~~\href{../text/types.html#text-valtype}{\mathtt{valtype}}^\ast~~\def\mathdef2611#1{\mbox{‘}\mathtt{#1}\mbox{’}}\mathdef2611{)} &\equiv&
(\def\mathdef2612#1{\mbox{‘}\mathtt{#1}\mbox{’}}\mathdef2612{(}~~\def\mathdef2613#1{\mbox{‘}\mathtt{#1}\mbox{’}}\mathdef2613{result}~~\href{../text/types.html#text-valtype}{\mathtt{valtype}}~~\def\mathdef2614#1{\mbox{‘}\mathtt{#1}\mbox{’}}\mathdef2614{)})^\ast \\
\end{array}\end{split}\]
Limits¶
\[\begin{split}\begin{array}{llclll}
\def\mathdef2553#1{{}}\mathdef2553{limits} & \href{../text/types.html#text-limits}{\mathtt{limits}} &::=&
n{:}\href{../text/values.html#text-int}{\def\mathdef2578#1{{\mathtt{u}#1}}\mathdef2578{\mathtt{32}}} &\Rightarrow& \{ \href{../syntax/types.html#syntax-limits}{\mathsf{min}}~n, \href{../syntax/types.html#syntax-limits}{\mathsf{max}}~\epsilon \} \\ &&|&
n{:}\href{../text/values.html#text-int}{\def\mathdef2578#1{{\mathtt{u}#1}}\mathdef2578{\mathtt{32}}}~~m{:}\href{../text/values.html#text-int}{\def\mathdef2578#1{{\mathtt{u}#1}}\mathdef2578{\mathtt{32}}} &\Rightarrow& \{ \href{../syntax/types.html#syntax-limits}{\mathsf{min}}~n, \href{../syntax/types.html#syntax-limits}{\mathsf{max}}~m \} \\
\end{array}\end{split}\]
Memory Types¶
\[\begin{split}\begin{array}{llclll@{\qquad\qquad}l}
\def\mathdef2553#1{{}}\mathdef2553{memory type} & \href{../text/types.html#text-memtype}{\mathtt{memtype}} &::=&
\mathit{lim}{:}\href{../text/types.html#text-limits}{\mathtt{limits}} &\Rightarrow& \mathit{lim} \\
\end{array}\end{split}\]
Table Types¶
\[\begin{split}\begin{array}{llclll}
\def\mathdef2553#1{{}}\mathdef2553{table type} & \href{../text/types.html#text-tabletype}{\mathtt{tabletype}} &::=&
\mathit{lim}{:}\href{../text/types.html#text-limits}{\mathtt{limits}}~~\mathit{et}{:}\href{../text/types.html#text-elemtype}{\mathtt{elemtype}} &\Rightarrow& \mathit{lim}~\mathit{et} \\
\def\mathdef2553#1{{}}\mathdef2553{element type} & \href{../text/types.html#text-elemtype}{\mathtt{elemtype}} &::=&
\def\mathdef2615#1{\mbox{‘}\mathtt{#1}\mbox{’}}\mathdef2615{funcref} &\Rightarrow& \href{../syntax/types.html#syntax-elemtype}{\mathsf{funcref}} \\
\end{array}\end{split}\]
Note
Additional element types may be introduced in future versions of WebAssembly.
Global Types¶
\[\begin{split}\begin{array}{llclll}
\def\mathdef2553#1{{}}\mathdef2553{global type} & \href{../text/types.html#text-globaltype}{\mathtt{globaltype}} &::=&
t{:}\href{../text/types.html#text-valtype}{\mathtt{valtype}} &\Rightarrow& \href{../syntax/types.html#syntax-mut}{\mathsf{const}}~t \\ &&|&
\def\mathdef2616#1{\mbox{‘}\mathtt{#1}\mbox{’}}\mathdef2616{(}~\def\mathdef2617#1{\mbox{‘}\mathtt{#1}\mbox{’}}\mathdef2617{mut}~~t{:}\href{../text/types.html#text-valtype}{\mathtt{valtype}}~\def\mathdef2618#1{\mbox{‘}\mathtt{#1}\mbox{’}}\mathdef2618{)} &\Rightarrow& \href{../syntax/types.html#syntax-mut}{\mathsf{var}}~t \\
\end{array}\end{split}\]