Tengo is a small, dynamic, fast, secure script language for Go.
Tengo is fast and secure because it's compiled/executed as bytecode on stack-based VM that's written in native Go.
/* The Tengo Language */
fmt := import("fmt")
each := func(seq, fn) {
    for x in seq { fn(x) }
}
sum := func(init, seq) {
    each(seq, func(x) { init += x })
    return init
}
fmt.println(sum(0, [1, 2, 3]))   // "6"
fmt.println(sum("", [1, 2, 3]))  // "123"Test this Tengo code in the Tengo Playground
- Simple and highly readable
Syntax
- Dynamic typing with type coercion
- Higher-order functions and closures
- Immutable values
 
- Securely Embeddable and Extensible
- Compiler/runtime written in native Go (no external deps or cgo)
- Executable as a standalone language / REPL
- Use cases: rules engine, state machine, data pipeline, transpiler
| fib(35) | fibt(35) | Language (Type) | |
|---|---|---|---|
| Tengo | 2,315ms | 3ms | Tengo (VM) | 
| go-lua | 4,028ms | 3ms | Lua (VM) | 
| GopherLua | 4,409ms | 3ms | Lua (VM) | 
| goja | 5,194ms | 4ms | JavaScript (VM) | 
| starlark-go | 6,954ms | 3ms | Starlark (Interpreter) | 
| gpython | 11,324ms | 4ms | Python (Interpreter) | 
| Yaegi | 11,715ms | 10ms | Yaegi (Interpreter) | 
| otto | 48,539ms | 6ms | JavaScript (Interpreter) | 
| Anko | 52,821ms | 6ms | Anko (Interpreter) | 
| - | - | - | - | 
| Go | 47ms | 2ms | Go (Native) | 
| Lua | 756ms | 2ms | Lua (Native) | 
| Python | 1,907ms | 14ms | Python2 (Native) | 
* fib(35):
Fibonacci(35)
* fibt(35):
tail-call version of Fibonacci(35)
* Go does not read the source code from file, while all other cases do
* See here for commands/codes used
go get github.com/d5/tengo/v2
A simple Go example code that compiles/runs Tengo script code with some input/output values:
package main
import (
	"context"
	"fmt"
	"github.com/d5/tengo/v2"
)
func main() {
	// create a new Script instance
	script := tengo.NewScript([]byte(
`each := func(seq, fn) {
    for x in seq { fn(x) }
}
sum := 0
mul := 1
each([a, b, c, d], func(x) {
    sum += x
    mul *= x
})`))
	// set values
	_ = script.Add("a", 1)
	_ = script.Add("b", 9)
	_ = script.Add("c", 8)
	_ = script.Add("d", 4)
	// run the script
	compiled, err := script.RunContext(context.Background())
	if err != nil {
		panic(err)
	}
	// retrieve values
	sum := compiled.Get("sum")
	mul := compiled.Get("mul")
	fmt.Println(sum, mul) // "22 288"
}Or, if you need to evaluate a simple expression, you can use Eval function instead:
res, err := tengo.Eval(ctx,
	`input ? "success" : "fail"`,
	map[string]interface{}{"input": 1})
if err != nil {
	panic(err)
}
fmt.Println(res) // "success"- Language Syntax
- Object Types
- Runtime Types and Operators
- Builtin Functions
- Interoperability
- Tengo CLI
- Standard Library
- Syntax Highlighters: VSCode, Atom
- Why the name Tengo? It's from 1Q84.