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https://github.com/d5/tengo

A fast script language for Go
https://github.com/d5/tengo

compiler embedded-language go golang programming-language script tengo vm

Last synced: 5 days ago
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A fast script language for Go

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# The Tengo Language



[![GoDoc](https://godoc.org/github.com/d5/tengo/v2?status.svg)](https://godoc.org/github.com/d5/tengo/v2)

![test](https://github.com/d5/tengo/workflows/test/badge.svg)

[![Go Report Card](https://goreportcard.com/badge/github.com/d5/tengo)](https://goreportcard.com/report/github.com/d5/tengo)



**Tengo is a small, dynamic, fast, secure script language for Go.** 



Tengo is **[fast](#benchmark)** and secure because it's compiled/executed as

bytecode on stack-based VM that's written in native Go.



```golang

/* 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](https://tengolang.com/?s=0c8d5d0d88f2795a7093d7f35ae12c3afa17bea3)



## Features



- Simple and highly readable

  [Syntax](https://github.com/d5/tengo/blob/master/docs/tutorial.md)

  - Dynamic typing with type coercion

  - Higher-order functions and closures

  - Immutable values

- [Securely Embeddable](https://github.com/d5/tengo/blob/master/docs/interoperability.md)

  and [Extensible](https://github.com/d5/tengo/blob/master/docs/objects.md)

- Compiler/runtime written in native Go _(no external deps or cgo)_

- Executable as a

  [standalone](https://github.com/d5/tengo/blob/master/docs/tengo-cli.md)

  language / REPL

- Use cases: rules engine, [state machine](https://github.com/d5/go-fsm),

  data pipeline, [transpiler](https://github.com/d5/tengo2lua)



## Benchmark



| | fib(35) | fibt(35) |  Language (Type)  |

| :--- |    ---: |     ---: |  :---: |

| [**Tengo**](https://github.com/d5/tengo) | `2,315ms` | `3ms` | Tengo (VM) |

| [go-lua](https://github.com/Shopify/go-lua) | `4,028ms` | `3ms` | Lua (VM) |

| [GopherLua](https://github.com/yuin/gopher-lua) | `4,409ms` | `3ms` | Lua (VM) |

| [goja](https://github.com/dop251/goja) | `5,194ms` | `4ms` | JavaScript (VM) |

| [starlark-go](https://github.com/google/starlark-go) | `6,954ms` | `3ms` | Starlark (Interpreter) |

| [gpython](https://github.com/go-python/gpython) | `11,324ms` | `4ms` | Python (Interpreter) |

| [Yaegi](https://github.com/containous/yaegi) | `11,715ms` | `10ms` | Yaegi (Interpreter) |

| [otto](https://github.com/robertkrimen/otto) | `48,539ms` | `6ms` | JavaScript (Interpreter) |

| [Anko](https://github.com/mattn/anko) | `52,821ms` | `6ms` | Anko (Interpreter) |

| - | - | - | - |

| Go | `47ms` | `2ms` | Go (Native) |

| Lua | `756ms` | `2ms` | Lua (Native) |

| Python | `1,907ms` | `14ms` | Python2 (Native) |



_* [fib(35)](https://github.com/d5/tengobench/blob/master/code/fib.tengo):

Fibonacci(35)_  

_* [fibt(35)](https://github.com/d5/tengobench/blob/master/code/fibtc.tengo):

[tail-call](https://en.wikipedia.org/wiki/Tail_call) version of Fibonacci(35)_  

_* **Go** does not read the source code from file, while all other cases do_  

_* See [here](https://github.com/d5/tengobench) 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:



```golang

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](https://pkg.go.dev/github.com/d5/tengo/v2#Eval) function instead:



```golang

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](https://github.com/d5/tengo/blob/master/docs/tutorial.md)

- [Object Types](https://github.com/d5/tengo/blob/master/docs/objects.md)

- [Runtime Types](https://github.com/d5/tengo/blob/master/docs/runtime-types.md)

  and [Operators](https://github.com/d5/tengo/blob/master/docs/operators.md)

- [Builtin Functions](https://github.com/d5/tengo/blob/master/docs/builtins.md)

- [Interoperability](https://github.com/d5/tengo/blob/master/docs/interoperability.md)

- [Tengo CLI](https://github.com/d5/tengo/blob/master/docs/tengo-cli.md)

- [Standard Library](https://github.com/d5/tengo/blob/master/docs/stdlib.md)

- Syntax Highlighters: [VSCode](https://github.com/lissein/vscode-tengo), [Atom](https://github.com/d5/tengo-atom), [Vim](https://github.com/geseq/tengo-vim)

- **Why the name Tengo?** It's from [1Q84](https://en.wikipedia.org/wiki/1Q84).