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 */

each := func(seq, fn) {
    for x in seq { fn(x) }
}

sum := func(init, seq) {
    each(seq, func(x) { init += x })
    return init
}

n := sum(0, [1, 2, 3])   // == 6
s := sum("", [1, 2, 3])  // == "123"

Run this code in the Playground

Features

• Simple and highly readable Syntax
  • Dynamic typing with type coercion
  • Higher-order functions and closures
  • Immutable values (v1)
  • Garbage collection
• Securely Embeddable and Extensible
• Compiler/runtime written in native Go (no external deps or cgo)
• Executable as a standalone language / REPL

Benchmark

	fib(35)	fibt(35)	Type
Go	58ms	3ms	Go (native)
Tengo	4,245ms	5ms	VM on Go
Lua	1,739ms	3ms	Lua (native)
go-lua	5,368ms	5ms	Lua VM on Go
GopherLua	5,408ms	5ms	Lua VM on Go
Python	3,176ms	27ms	Python (native)
starlark-go	15,400ms	5ms	Python-like Interpreter on Go
gpython	17,724ms	6ms	Python Interpreter on Go
otto	82,050ms	22ms	JS Interpreter on Go
Anko	98,739ms	31ms	Interpreter on Go

* 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

References

• Language Syntax
• Tengo Objects
• Runtime Types
• Builtin Functions
• Interoperability
• Tengo CLI
• Standard Library (experimental)

Roadmap

v0. (Current)

Things are experimental, and, the focus is on the core language features, stability, basic interoperability, and the performance optimization.

v1. Tengo as a Script Language

This will be the first versioned release, and, the main goal for v1 is to make Tengo as a fast embeddable script language for Go, which means Tengo will be comparable to other Go-based script languages such as Starlark, Lua VMs, and other interpreters.

• Interoperability with Go code
• Sandbox environment
• More language features

v2. Tengo as a Standalone Language

• Language-level concurrency support
• Tengo Standard Libraries
• Native executables compilation
• More language features