Types¶
Value Types¶
\[\begin{split}\begin{array}{llcll@{\qquad\qquad}l}
\def\mathdef3128#1{{}}\mathdef3128{value type} & \href{../text/types.html#text-valtype}{\mathtt{valtype}} &::=&
\def\mathdef3185#1{\mbox{‘}\mathtt{#1}\mbox{’}}\mathdef3185{i32} &\Rightarrow& \href{../syntax/types.html#syntax-valtype}{\mathsf{i32}} \\ &&|&
\def\mathdef3186#1{\mbox{‘}\mathtt{#1}\mbox{’}}\mathdef3186{i64} &\Rightarrow& \href{../syntax/types.html#syntax-valtype}{\mathsf{i64}} \\ &&|&
\def\mathdef3187#1{\mbox{‘}\mathtt{#1}\mbox{’}}\mathdef3187{f32} &\Rightarrow& \href{../syntax/types.html#syntax-valtype}{\mathsf{f32}} \\ &&|&
\def\mathdef3188#1{\mbox{‘}\mathtt{#1}\mbox{’}}\mathdef3188{f64} &\Rightarrow& \href{../syntax/types.html#syntax-valtype}{\mathsf{f64}} \\
\end{array}\end{split}\]
Result Types¶
\[\begin{split}\begin{array}{llclll@{\qquad\qquad}l}
\def\mathdef3128#1{{}}\mathdef3128{result type} & \href{../text/types.html#text-resulttype}{\mathtt{resulttype}} &::=&
(t{:}\href{../text/types.html#text-functype}{\mathtt{result}})^? &\Rightarrow& [t^?] \\
\end{array}\end{split}\]
Note
In future versions of WebAssembly, this scheme may be extended to support multiple results or more general result types.
Function Types¶
\[\begin{split}\begin{array}{llclll@{\qquad\qquad}l}
\def\mathdef3128#1{{}}\mathdef3128{function type} & \href{../text/types.html#text-functype}{\mathtt{functype}} &::=&
\def\mathdef3189#1{\mbox{‘}\mathtt{#1}\mbox{’}}\mathdef3189{(}~\def\mathdef3190#1{\mbox{‘}\mathtt{#1}\mbox{’}}\mathdef3190{func}~~t_1^\ast{:\,}\href{../text/conventions.html#text-vec}{\mathtt{vec}}(\href{../text/types.html#text-functype}{\mathtt{param}})~~t_2^\ast{:\,}\href{../text/conventions.html#text-vec}{\mathtt{vec}}(\href{../text/types.html#text-functype}{\mathtt{result}})~\def\mathdef3191#1{\mbox{‘}\mathtt{#1}\mbox{’}}\mathdef3191{)}
&\Rightarrow& [t_1^\ast] \href{../syntax/types.html#syntax-functype}{\rightarrow} [t_2^\ast] \\
\def\mathdef3128#1{{}}\mathdef3128{parameter} & \href{../text/types.html#text-functype}{\mathtt{param}} &::=&
\def\mathdef3192#1{\mbox{‘}\mathtt{#1}\mbox{’}}\mathdef3192{(}~\def\mathdef3193#1{\mbox{‘}\mathtt{#1}\mbox{’}}\mathdef3193{param}~~\href{../text/values.html#text-id}{\mathtt{id}}^?~~t{:}\href{../text/types.html#text-valtype}{\mathtt{valtype}}~\def\mathdef3194#1{\mbox{‘}\mathtt{#1}\mbox{’}}\mathdef3194{)}
&\Rightarrow& t \\
\def\mathdef3128#1{{}}\mathdef3128{result} & \href{../text/types.html#text-functype}{\mathtt{result}} &::=&
\def\mathdef3195#1{\mbox{‘}\mathtt{#1}\mbox{’}}\mathdef3195{(}~\def\mathdef3196#1{\mbox{‘}\mathtt{#1}\mbox{’}}\mathdef3196{result}~~t{:}\href{../text/types.html#text-valtype}{\mathtt{valtype}}~\def\mathdef3197#1{\mbox{‘}\mathtt{#1}\mbox{’}}\mathdef3197{)}
&\Rightarrow& t \\
\end{array}\end{split}\]
Abbreviations¶
Multiple anonymous parameters or results may be combined into a single declaration:
\[\begin{split}\begin{array}{llclll}
\def\mathdef3128#1{{}}\mathdef3128{parameter} &
\def\mathdef3198#1{\mbox{‘}\mathtt{#1}\mbox{’}}\mathdef3198{(}~~\def\mathdef3199#1{\mbox{‘}\mathtt{#1}\mbox{’}}\mathdef3199{param}~~\href{../text/types.html#text-valtype}{\mathtt{valtype}}^\ast~~\def\mathdef3200#1{\mbox{‘}\mathtt{#1}\mbox{’}}\mathdef3200{)} &\equiv&
(\def\mathdef3201#1{\mbox{‘}\mathtt{#1}\mbox{’}}\mathdef3201{(}~~\def\mathdef3202#1{\mbox{‘}\mathtt{#1}\mbox{’}}\mathdef3202{param}~~\href{../text/types.html#text-valtype}{\mathtt{valtype}}~~\def\mathdef3203#1{\mbox{‘}\mathtt{#1}\mbox{’}}\mathdef3203{)})^\ast \\
\def\mathdef3128#1{{}}\mathdef3128{result} &
\def\mathdef3204#1{\mbox{‘}\mathtt{#1}\mbox{’}}\mathdef3204{(}~~\def\mathdef3205#1{\mbox{‘}\mathtt{#1}\mbox{’}}\mathdef3205{result}~~\href{../text/types.html#text-valtype}{\mathtt{valtype}}^\ast~~\def\mathdef3206#1{\mbox{‘}\mathtt{#1}\mbox{’}}\mathdef3206{)} &\equiv&
(\def\mathdef3207#1{\mbox{‘}\mathtt{#1}\mbox{’}}\mathdef3207{(}~~\def\mathdef3208#1{\mbox{‘}\mathtt{#1}\mbox{’}}\mathdef3208{result}~~\href{../text/types.html#text-valtype}{\mathtt{valtype}}~~\def\mathdef3209#1{\mbox{‘}\mathtt{#1}\mbox{’}}\mathdef3209{)})^\ast \\
\end{array}\end{split}\]
Limits¶
\[\begin{split}\begin{array}{llclll}
\def\mathdef3128#1{{}}\mathdef3128{limits} & \href{../text/types.html#text-limits}{\mathtt{limits}} &::=&
n{:}\href{../text/values.html#text-int}{\def\mathdef3173#1{{\mathtt{u}#1}}\mathdef3173{\mathtt{32}}} &\Rightarrow& \{ \href{../syntax/types.html#syntax-limits}{\mathsf{min}}~n, \href{../syntax/types.html#syntax-limits}{\mathsf{max}}~\epsilon \} \\ &&|&
n{:}\href{../text/values.html#text-int}{\def\mathdef3173#1{{\mathtt{u}#1}}\mathdef3173{\mathtt{32}}}~~m{:}\href{../text/values.html#text-int}{\def\mathdef3173#1{{\mathtt{u}#1}}\mathdef3173{\mathtt{32}}} &\Rightarrow& \{ \href{../syntax/types.html#syntax-limits}{\mathsf{min}}~n, \href{../syntax/types.html#syntax-limits}{\mathsf{max}}~m \} \\
\end{array}\end{split}\]
Memory Types¶
\[\begin{split}\begin{array}{llclll@{\qquad\qquad}l}
\def\mathdef3128#1{{}}\mathdef3128{memory type} & \href{../text/types.html#text-memtype}{\mathtt{memtype}} &::=&
\mathit{lim}{:}\href{../text/types.html#text-limits}{\mathtt{limits}} &\Rightarrow& \mathit{lim} \\
\end{array}\end{split}\]
Table Types¶
\[\begin{split}\begin{array}{llclll}
\def\mathdef3128#1{{}}\mathdef3128{table type} & \href{../text/types.html#text-tabletype}{\mathtt{tabletype}} &::=&
\mathit{lim}{:}\href{../text/types.html#text-limits}{\mathtt{limits}}~~\mathit{et}{:}\href{../text/types.html#text-elemtype}{\mathtt{elemtype}} &\Rightarrow& \mathit{lim}~\mathit{et} \\
\def\mathdef3128#1{{}}\mathdef3128{element type} & \href{../text/types.html#text-elemtype}{\mathtt{elemtype}} &::=&
\def\mathdef3210#1{\mbox{‘}\mathtt{#1}\mbox{’}}\mathdef3210{anyfunc} &\Rightarrow& \href{../syntax/types.html#syntax-elemtype}{\mathsf{anyfunc}} \\
\end{array}\end{split}\]
Note
Additional element types may be introduced in future versions of WebAssembly.
Global Types¶
\[\begin{split}\begin{array}{llclll}
\def\mathdef3128#1{{}}\mathdef3128{global type} & \href{../text/types.html#text-globaltype}{\mathtt{globaltype}} &::=&
t{:}\href{../text/types.html#text-valtype}{\mathtt{valtype}} &\Rightarrow& \href{../syntax/types.html#syntax-mut}{\mathsf{const}}~t \\ &&|&
\def\mathdef3211#1{\mbox{‘}\mathtt{#1}\mbox{’}}\mathdef3211{(}~\def\mathdef3212#1{\mbox{‘}\mathtt{#1}\mbox{’}}\mathdef3212{mut}~~t{:}\href{../text/types.html#text-valtype}{\mathtt{valtype}}~\def\mathdef3213#1{\mbox{‘}\mathtt{#1}\mbox{’}}\mathdef3213{)} &\Rightarrow& \href{../syntax/types.html#syntax-mut}{\mathsf{var}}~t \\
\end{array}\end{split}\]