Documentation
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Overview ¶
Package assemblyscript contains Go-defined special functions imported by AssemblyScript under the module name "env".
Special Functions ¶
AssemblyScript code import the below special functions when not using WASI. Note: Sometimes only "abort" is imported.
- "abort" - exits with 255 with an abort message written to wazero.ModuleConfig WithStderr.
- "trace" - no output unless.
- "seed" - uses wazero.ModuleConfig WithRandSource as the source of seed values.
See https://www.assemblyscript.org/concepts.html#special-imports
Relationship to WASI ¶
AssemblyScript supports compiling JavaScript functions that use I/O, such as `console.log("hello")`. However, WASI is not built-in to AssemblyScript. Use the `wasi-shim` to compile if you get import errors.
See https://github.com/AssemblyScript/wasi-shim#usage and wasi_snapshot_preview1.Instantiate for more.
Example (FunctionExporter) ¶
This shows how to instantiate AssemblyScript's special imports when you also need other functions in the "env" module.
ctx := context.Background()
r := wazero.NewRuntime(ctx)
defer r.Close(ctx) // This closes everything this Runtime created.
// First construct your own module builder for "env"
envBuilder := r.NewHostModuleBuilder("env").
NewFunctionBuilder().
WithFunc(func() uint32 { return 1 }).
Export("get_int")
// Now, add AssemblyScript special function imports into it.
NewFunctionExporter().
WithAbortMessageDisabled().
ExportFunctions(envBuilder)
Example (Instantiate) ¶
This shows how to instantiate AssemblyScript's special imports.
ctx := context.Background() r := wazero.NewRuntime(ctx) defer r.Close(ctx) // This closes everything this Runtime created. // This adds the "env" module to the runtime, with AssemblyScript's special // function imports. MustInstantiate(ctx, r)
Index ¶
Examples ¶
Constants ¶
This section is empty.
Variables ¶
This section is empty.
Functions ¶
func Instantiate ¶
Instantiate instantiates the "env" module used by AssemblyScript into the runtime.
Notes ¶
- Failure cases are documented on wazero.Runtime InstantiateModule.
- Closing the wazero.Runtime has the same effect as closing the result.
- To add more functions to the "env" module, use FunctionExporter.
Types ¶
type FunctionExporter ¶
type FunctionExporter interface {
// WithAbortMessageDisabled configures the AssemblyScript abort function to
// discard any message.
WithAbortMessageDisabled() FunctionExporter
// WithTraceToStdout configures the AssemblyScript trace function to output
// messages to Stdout, as configured by wazero.ModuleConfig WithStdout.
WithTraceToStdout() FunctionExporter
// WithTraceToStderr configures the AssemblyScript trace function to output
// messages to Stderr, as configured by wazero.ModuleConfig WithStderr.
//
// Because of the potential volume of trace messages, it is often more
// appropriate to use WithTraceToStdout instead.
WithTraceToStderr() FunctionExporter
// ExportFunctions builds functions to export with a wazero.HostModuleBuilder
// named "env".
ExportFunctions(wazero.HostModuleBuilder)
}
FunctionExporter configures the functions in the "env" module used by AssemblyScript.
Notes ¶
- This is an interface for decoupling, not third-party implementations. All implementations are in wazero.
func NewFunctionExporter ¶
func NewFunctionExporter() FunctionExporter
NewFunctionExporter returns a FunctionExporter object with trace disabled.
Source Files
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