Types¶

Number Types¶

\begin{array}{r} \begin{array}{llclll} {numtype}_{I} & ::= & ‘ i 32 ’ & \Rightarrow & i 32 \\ | & ‘ i 64 ’ & \Rightarrow & i 64 \\ | & ‘ f 32 ’ & \Rightarrow & f 32 \\ | & ‘ f 64 ’ & \Rightarrow & f 64 \end{array} \end{array}

Vector Types¶

\begin{array}{r} \begin{array}{llclll} {vectype}_{I} & ::= & ‘ v 128 ’ & \Rightarrow & v 128 \end{array} \end{array}

Heap Types¶

\begin{array}{r} \begin{array}{llclll} {heaptype}_{I} & ::= & ‘ func ’ & \Rightarrow & func \\ | & ‘ extern ’ & \Rightarrow & extern \\ | & x : {typeidx}_{I} & \Rightarrow & x \end{array} \end{array}

Reference Types¶

\begin{array}{r} \begin{array}{llclll} {reftype}_{I} & ::= & ‘ (’ ‘ ref ’ ht : heaptype ‘) ’ & \Rightarrow & ref ht \\ | & ‘ (’ ‘ ref ’ ‘ null ’ ht : heaptype ‘) ’ & \Rightarrow & ref null ht \end{array} \end{array}

Abbreviations¶

There are shorthands for references to abstract heap types.

\begin{array}{r} \begin{array}{llclll} ‘ funcref ’ & \equiv & ‘ (’ ‘ ref ’ ‘ null ’ ‘ func ’ ‘) ’ \\ ‘ externref ’ & \equiv & ‘ (’ ‘ ref ’ ‘ null ’ ‘ extern ’ ‘) ’ \end{array} \end{array}

Value Types¶

\begin{array}{r} \begin{array}{llclll} {valtype}_{I} & ::= & t : {numtype}_{I} & \Rightarrow & t \\ | & t : {vectype}_{I} & \Rightarrow & t \\ | & t : {reftype}_{I} & \Rightarrow & t \end{array} \end{array}

Function Types¶

\begin{array}{r} \begin{array}{llcllll} {functype}_{I} & ::= & ‘ (’ ‘ func ’ t_{1}^{*} : vec ({param}_{I}) t_{2}^{*} : vec ({result}_{I}) ‘) ’ & \Rightarrow & [t_{1}^{*}] \to [t_{2}^{*}] \\ {param}_{I} & ::= & ‘ (’ ‘ param ’ {id}^{?} t : {valtype}_{I} ‘) ’ & \Rightarrow & t \\ {result}_{I} & ::= & ‘ (’ ‘ result ’ t : {valtype}_{I} ‘) ’ & \Rightarrow & t \end{array} \end{array}

Note

The optional identifier names for parameters in a function type only have documentation purpose. They cannot be referenced from anywhere.

Abbreviations¶

Multiple anonymous parameters or results may be combined into a single declaration:

\begin{array}{r} \begin{array}{llclll} ‘ (’ ‘ param ’ {valtype}^{*} ‘) ’ & \equiv & (‘ (’ ‘ param ’ valtype ‘) ’)^{*} \\ ‘ (’ ‘ result ’ {valtype}^{*} ‘) ’ & \equiv & (‘ (’ ‘ result ’ valtype ‘) ’)^{*} \end{array} \end{array}

Limits¶

\begin{array}{r} \begin{array}{llclll} limits & ::= & n : u 32 & \Rightarrow & {\min n, \max ϵ} \\ | & n : u 32 m : u 32 & \Rightarrow & {\min n, \max m} \end{array} \end{array}

Memory Types¶

\begin{array}{r} \begin{array}{llcllll} {memtype}_{I} & ::= & \lim : limits & \Rightarrow & \lim \end{array} \end{array}

Table Types¶

\begin{array}{r} \begin{array}{llclll} {tabletype}_{I} & ::= & \lim : limits et : {reftype}_{I} & \Rightarrow & \lim et \end{array} \end{array}

Global Types¶

\begin{array}{r} \begin{array}{llclll} {globaltype}_{I} & ::= & t : valtype & \Rightarrow & const t \\ | & ‘ (’ ‘ mut ’ t : {valtype}_{I} ‘) ’ & \Rightarrow & var t \end{array} \end{array}