Types¶
Value Types¶
\[\begin{split}\begin{array}{llcll@{\qquad\qquad}l}
\def\mathdef3070#1{{}}\mathdef3070{value type} & \href{../text/types.html#text-valtype}{\mathtt{valtype}} &::=&
\def\mathdef3127#1{\mbox{‘}\mathtt{#1}\mbox{’}}\mathdef3127{i32} &\Rightarrow& \href{../syntax/types.html#syntax-valtype}{\mathsf{i32}} \\ &&|&
\def\mathdef3128#1{\mbox{‘}\mathtt{#1}\mbox{’}}\mathdef3128{i64} &\Rightarrow& \href{../syntax/types.html#syntax-valtype}{\mathsf{i64}} \\ &&|&
\def\mathdef3129#1{\mbox{‘}\mathtt{#1}\mbox{’}}\mathdef3129{f32} &\Rightarrow& \href{../syntax/types.html#syntax-valtype}{\mathsf{f32}} \\ &&|&
\def\mathdef3130#1{\mbox{‘}\mathtt{#1}\mbox{’}}\mathdef3130{f64} &\Rightarrow& \href{../syntax/types.html#syntax-valtype}{\mathsf{f64}} \\
\end{array}\end{split}\]
Result Types¶
\[\begin{split}\begin{array}{llclll@{\qquad\qquad}l}
\def\mathdef3070#1{{}}\mathdef3070{result type} & \href{../text/types.html#text-resulttype}{\mathtt{resulttype}} &::=&
(t{:}\href{../text/types.html#text-functype}{\mathtt{result}})^? &\Rightarrow& [t^?] \\
\end{array}\end{split}\]
Note
In future versions of WebAssembly, this scheme may be extended to support multiple results or more general result types.
Function Types¶
\[\begin{split}\begin{array}{llclll@{\qquad\qquad}l}
\def\mathdef3070#1{{}}\mathdef3070{function type} & \href{../text/types.html#text-functype}{\mathtt{functype}} &::=&
\def\mathdef3131#1{\mbox{‘}\mathtt{#1}\mbox{’}}\mathdef3131{(}~\def\mathdef3132#1{\mbox{‘}\mathtt{#1}\mbox{’}}\mathdef3132{func}~~t_1^\ast{:\,}\href{../text/conventions.html#text-vec}{\mathtt{vec}}(\href{../text/types.html#text-functype}{\mathtt{param}})~~t_2^\ast{:\,}\href{../text/conventions.html#text-vec}{\mathtt{vec}}(\href{../text/types.html#text-functype}{\mathtt{result}})~\def\mathdef3133#1{\mbox{‘}\mathtt{#1}\mbox{’}}\mathdef3133{)}
&\Rightarrow& [t_1^\ast] \href{../syntax/types.html#syntax-functype}{\rightarrow} [t_2^\ast] \\
\def\mathdef3070#1{{}}\mathdef3070{parameter} & \href{../text/types.html#text-functype}{\mathtt{param}} &::=&
\def\mathdef3134#1{\mbox{‘}\mathtt{#1}\mbox{’}}\mathdef3134{(}~\def\mathdef3135#1{\mbox{‘}\mathtt{#1}\mbox{’}}\mathdef3135{param}~~\href{../text/values.html#text-id}{\mathtt{id}}^?~~t{:}\href{../text/types.html#text-valtype}{\mathtt{valtype}}~\def\mathdef3136#1{\mbox{‘}\mathtt{#1}\mbox{’}}\mathdef3136{)}
&\Rightarrow& t \\
\def\mathdef3070#1{{}}\mathdef3070{result} & \href{../text/types.html#text-functype}{\mathtt{result}} &::=&
\def\mathdef3137#1{\mbox{‘}\mathtt{#1}\mbox{’}}\mathdef3137{(}~\def\mathdef3138#1{\mbox{‘}\mathtt{#1}\mbox{’}}\mathdef3138{result}~~t{:}\href{../text/types.html#text-valtype}{\mathtt{valtype}}~\def\mathdef3139#1{\mbox{‘}\mathtt{#1}\mbox{’}}\mathdef3139{)}
&\Rightarrow& t \\
\end{array}\end{split}\]
Abbreviations¶
Multiple anonymous parameters or results may be combined into a single declaration:
\[\begin{split}\begin{array}{llclll}
\def\mathdef3070#1{{}}\mathdef3070{parameter} &
\def\mathdef3140#1{\mbox{‘}\mathtt{#1}\mbox{’}}\mathdef3140{(}~~\def\mathdef3141#1{\mbox{‘}\mathtt{#1}\mbox{’}}\mathdef3141{param}~~\href{../text/types.html#text-valtype}{\mathtt{valtype}}^\ast~~\def\mathdef3142#1{\mbox{‘}\mathtt{#1}\mbox{’}}\mathdef3142{)} &\equiv&
(\def\mathdef3143#1{\mbox{‘}\mathtt{#1}\mbox{’}}\mathdef3143{(}~~\def\mathdef3144#1{\mbox{‘}\mathtt{#1}\mbox{’}}\mathdef3144{param}~~\href{../text/types.html#text-valtype}{\mathtt{valtype}}~~\def\mathdef3145#1{\mbox{‘}\mathtt{#1}\mbox{’}}\mathdef3145{)})^\ast \\
\def\mathdef3070#1{{}}\mathdef3070{result} &
\def\mathdef3146#1{\mbox{‘}\mathtt{#1}\mbox{’}}\mathdef3146{(}~~\def\mathdef3147#1{\mbox{‘}\mathtt{#1}\mbox{’}}\mathdef3147{result}~~\href{../text/types.html#text-valtype}{\mathtt{valtype}}^\ast~~\def\mathdef3148#1{\mbox{‘}\mathtt{#1}\mbox{’}}\mathdef3148{)} &\equiv&
(\def\mathdef3149#1{\mbox{‘}\mathtt{#1}\mbox{’}}\mathdef3149{(}~~\def\mathdef3150#1{\mbox{‘}\mathtt{#1}\mbox{’}}\mathdef3150{result}~~\href{../text/types.html#text-valtype}{\mathtt{valtype}}~~\def\mathdef3151#1{\mbox{‘}\mathtt{#1}\mbox{’}}\mathdef3151{)})^\ast \\
\end{array}\end{split}\]
Limits¶
\[\begin{split}\begin{array}{llclll}
\def\mathdef3070#1{{}}\mathdef3070{limits} & \href{../text/types.html#text-limits}{\mathtt{limits}} &::=&
n{:}\href{../text/values.html#text-int}{\def\mathdef3115#1{{\mathtt{u}#1}}\mathdef3115{\mathtt{32}}} &\Rightarrow& \{ \href{../syntax/types.html#syntax-limits}{\mathsf{min}}~n, \href{../syntax/types.html#syntax-limits}{\mathsf{max}}~\epsilon \} \\ &&|&
n{:}\href{../text/values.html#text-int}{\def\mathdef3115#1{{\mathtt{u}#1}}\mathdef3115{\mathtt{32}}}~~m{:}\href{../text/values.html#text-int}{\def\mathdef3115#1{{\mathtt{u}#1}}\mathdef3115{\mathtt{32}}} &\Rightarrow& \{ \href{../syntax/types.html#syntax-limits}{\mathsf{min}}~n, \href{../syntax/types.html#syntax-limits}{\mathsf{max}}~m \} \\
\end{array}\end{split}\]
Memory Types¶
\[\begin{split}\begin{array}{llclll@{\qquad\qquad}l}
\def\mathdef3070#1{{}}\mathdef3070{memory type} & \href{../text/types.html#text-memtype}{\mathtt{memtype}} &::=&
\mathit{lim}{:}\href{../text/types.html#text-limits}{\mathtt{limits}} &\Rightarrow& \mathit{lim} \\
\end{array}\end{split}\]
Table Types¶
\[\begin{split}\begin{array}{llclll}
\def\mathdef3070#1{{}}\mathdef3070{table type} & \href{../text/types.html#text-tabletype}{\mathtt{tabletype}} &::=&
\mathit{lim}{:}\href{../text/types.html#text-limits}{\mathtt{limits}}~~\mathit{et}{:}\href{../text/types.html#text-elemtype}{\mathtt{elemtype}} &\Rightarrow& \mathit{lim}~\mathit{et} \\
\def\mathdef3070#1{{}}\mathdef3070{element type} & \href{../text/types.html#text-elemtype}{\mathtt{elemtype}} &::=&
\def\mathdef3152#1{\mbox{‘}\mathtt{#1}\mbox{’}}\mathdef3152{anyfunc} &\Rightarrow& \href{../syntax/types.html#syntax-elemtype}{\mathsf{anyfunc}} \\
\end{array}\end{split}\]
Note
Additional element types may be introduced in future versions of WebAssembly.
Global Types¶
\[\begin{split}\begin{array}{llclll}
\def\mathdef3070#1{{}}\mathdef3070{global type} & \href{../text/types.html#text-globaltype}{\mathtt{globaltype}} &::=&
t{:}\href{../text/types.html#text-valtype}{\mathtt{valtype}} &\Rightarrow& \href{../syntax/types.html#syntax-mut}{\mathsf{const}}~t \\ &&|&
\def\mathdef3153#1{\mbox{‘}\mathtt{#1}\mbox{’}}\mathdef3153{(}~\def\mathdef3154#1{\mbox{‘}\mathtt{#1}\mbox{’}}\mathdef3154{mut}~~t{:}\href{../text/types.html#text-valtype}{\mathtt{valtype}}~\def\mathdef3155#1{\mbox{‘}\mathtt{#1}\mbox{’}}\mathdef3155{)} &\Rightarrow& \href{../syntax/types.html#syntax-mut}{\mathsf{var}}~t \\
\end{array}\end{split}\]