# The Tengo Language [](https://godoc.org/github.com/d5/tengo/script) [](https://goreportcard.com/report/github.com/d5/tengo) [](https://travis-ci.org/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 */ 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](https://tengolang.com/?s=d01cf9ed81daba939e26618530eb171f7397d9c9) ## 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 _(v1)_ - Garbage collection - [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 ## Benchmark | | fib(35) | fibt(35) | Type | | :--- | ---: | ---: | :---: | | Go | `58ms` | `3ms` | Go (native) | | [**Tengo**](https://github.com/d5/tengo) | `4,245ms` | `5ms` | VM on Go | | Lua | `1,739ms` | `3ms` | Lua (native) | | [go-lua](https://github.com/Shopify/go-lua) | `5,368ms` | `5ms` | Lua VM on Go | | [GopherLua](https://github.com/yuin/gopher-lua) | `5,408ms` | `5ms` | Lua VM on Go | | Python | `3,176ms` | `27ms` | Python (native) | | [starlark-go](https://github.com/google/starlark-go) | `15,400ms` | `5ms` | Python-like Interpreter on Go | | [gpython](https://github.com/go-python/gpython) | `17,724ms` | `6ms` | Python Interpreter on Go | | [otto](https://github.com/robertkrimen/otto) | `82,050ms` | `22ms` | JS Interpreter on Go | | [Anko](https://github.com/mattn/anko) | `98,739ms` | `31ms` | Interpreter on Go | _* [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_ ## References - [Language Syntax](https://github.com/d5/tengo/blob/master/docs/tutorial.md) - [Tengo Objects](https://github.com/d5/tengo/blob/master/docs/objects.md) - [Runtime Types](https://github.com/d5/tengo/blob/master/docs/runtime-types.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) _(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](https://github.com/d5/tengo/labels/v1.0) 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](https://github.com/google/starlark-go), [Lua](https://github.com/Shopify/go-lua) [VM](https://github.com/yuin/gopher-lua)s, and [other](https://github.com/robertkrimen/otto) [interpreter](https://github.com/mattn/anko)s. - 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