To execute Tengo code in your Go codebase, you should use **Script**. In the simple use cases, all you need is to do is to create a new Script instance and call its `Script.Run()` function.
```golang
import "github.com/d5/tengo/script"
var code = `
reduce := func(seq, fn) {
s := 0
for x in seq { fn(x, s) }
return s
}
print(reduce([1, 2, 3], func(x, s) { s += x }))
`
func main() {
s := script.New([]byte(code))
if _, err := s.Run(); err != nil {
panic(err)
}
}
```
If you want to compile the source script once and execute it multiple times, you can use `Script.Compile()` function that returns **Compiled** instance.
```golang
import (
"fmt"
"github.com/d5/tengo/script"
)
func main() {
s := script.New([]byte(`a := b + 20`))
// define variable 'b'
_ = s.Add("b", 10)
// compile the source
c, err := s.Compile()
if err != nil {
panic(err)
}
// run the compiled bytecode
// a compiled bytecode 'c' can be executed multiple without re-compiling it
if err := c.Run(); err != nil {
panic(err)
}
// retrieve value of 'a'
a := c.Get("a")
fmt.Println(a.Int())
}
```
In the example above, a variable `b` is defined by the user before compilation using `Script.Add()` function. Then a compiled bytecode `c` is used to execute the bytecode and get the value of global variables. In this example, the value of global variable `a` is read using `Compiled.Get()` function.
One can easily use the custom data types by implementing `objects.Object` interface. See [Interoperability](https://github.com/d5/tengo/wiki/Interoperability) for more details.
As an alternative to using **Script**, you can directly create and interact with the parser, compiler, and, VMs directly. There's no good documentation yet, but, check out Script code if you are interested.
