Call a plugin from guest code

Plugin imports are ordinary Wasm functions. Use the syntax your guest language already provides for imported functions.

This example calls tutorial.answer() -> i32.

(module
  (import "tutorial" "answer" (func $answer (result i32)))
  (func (export "run") (result i32)
    call $answer))

The module name, function name, parameters, and results must match the plugin declaration.

Run examples/22-language-guests to execute all three compiled guests against one host function. Run the pinned example directly from any directory:

go run github.com/wago-org/wago/examples/22-language-guests@b084a7c9343f81a9120ca80a13d133884e88d514

Expect WAT answer = 42, AssemblyScript answer = 42, and TinyGo answer = 42. Its build script reproduces the checked-in .wasm files.

Check the guest before loading it

From the wago-answer directory created in Write your first plugin, inspect the downloaded guest:

wago module imports testdata/answer.wasm
wago module exports testdata/answer.wasm

Expect an import named tutorial.answer with signature () -> i32 and an exported run. An unresolved import is expected here: the local Go test has not installed a CLI plugin. Run the local provider through its integration test:

go test ./register -run TestAnswerFromGuest -v

After publishing and installing your own plugin into the selected CLI runtime, the equivalent command is:

wago run testdata/answer.wasm --invoke run

The result is 42. --invoke run selects the same export consistently, including guests with several exports. Wago can auto-select the WAT example's sole run function even though it has no _start.

TinyGo reactor-style guests may also export _initialize. Call it once before run on the same instance when the guest needs initialization:

wago run path/to/tinygo/answer.wasm --invoke _initialize --invoke run

The checked-in language example handles that initialization for its TinyGo guest. The build script requires the matching guest toolchains; the Go test uses the existing binaries and does not need to install them.