tengo

The Tengo Language

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

Features

• 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

Benchmark

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

Quick Start

go get github.com/d5/tengo/v2

A simple Go example code that compiles/runs Tengo script code with some input/output values:

…

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"

References

• Language Syntax
• Object Types
• Runtime Types and Operators
• Builtin Functions
• Interoperability
• Tengo CLI
• Standard Library
• Syntax Highlighters: VSCode, Atom, Vim, Emacs
• Why the name Tengo? It's from 1Q84.