gem "wasmtime"

require "wasmtime"
# Create an engine. Generally, you only need a single engine and can
# re-use it throughout your program.
engine = Wasmtime::Engine.new
# Compile a Wasm module from either Wasm or WAT. The compiled module is
# specific to the Engine's configuration.
mod = Wasmtime::Module.new(engine, <<~WAT)
  (module
    (func $hello (import "" "hello"))
    (func (export "run") (call $hello))
  )
WAT
# Create a store. Store can keep state to be re-used in Funcs.
store = Wasmtime::Store.new(engine, {count: 0})
# Define a Wasm function from Ruby code.
func = Wasmtime::Func.new(store, [], []) do |caller|
  puts "Hello from Func!"
  caller.store_data[:count] += 1
  puts "Ran #{caller.store_data[:count]} time(s)"
end
# Build the Wasm instance by providing its imports.
instance = Wasmtime::Instance.new(store, mod, [func])
# Run the `run` export.
instance.invoke("run")
# Or: get the `run` export and call it.
instance.export("run").to_func.call