Choosing an interpreter for running executors #1
Description
Klio lifecycle commands need scripting language engine for running executors (builders, deployers, etc). Currently they are using goya, but it was chosen as a temporary solution, without evaluating other options.
Good interpreter should meet the following requirements:
- It has to be small - chosen engine is going to be included in every binary, it shouldn't add 3MB to each one of them.
- It should have good documentation for both itself and a language.
- It should have good standard library, otherwise we need to create it by our own.
Which engines are taken into consideration?
Stats as at 16 Sep 2021.
| Package | Language | Stars | Watchers | Forks | Last Commit |
|---|---|---|---|---|---|
| otto | JavaScript | 6222 | 189 | 521 | 14 Jun 2021 |
| goja | JavaScript | 2386 | 66 | 201 | 12 Sep 2021 |
| go-ducktape | JavaScript | 778 | 28 | 90 | 26 Mar 2021 |
| gopher-lua | Lua | 4289 | 149 | 477 | 29 May 2021 |
| go-lua | Lua | 2152 | 312 | 156 | 2 Mar 2021 |
| golua | Lua | 555 | 34 | 193 | 7 May 2021 |
| go-python | Python | 1303 | 43 | 128 | 14 Apr 2021 |
| gpython | Python | 517 | 21 | 58 | 18 Nov 2019 |
| yaegi | Golang | 3816 | 50 | 183 | 15 Sep 2021 |
| tengo | Tengo | 2422 | 57 | 141 | 5 Sep 2021 |
| starlark-go | Starlark | 1367 | 46 | 122 | 1 Sep 2021 |
| anko | Anko Script | 1167 | 47 | 111 | 21 May 2020 |
| go-php | PHP | 42 | 811 | 92 | 1 Oct 2018 |
Additional size of commands
Following numbers are based on interpreters integrated with build command, compared with
interpreter-less version.
| Package | Compressed | Uncompressed |
|---|---|---|
| goja | 3.19MB | 7.63MB |
| gopher-lua | 1.13MB | 2.47MB |
| otto | 1.21MB | 2.81MB |
| tengo | 0.36MB | 0.86MB |
Standard libraries
Relevant features supported by standard libraries:
| Package | File System | Exec | HTTP | Regex | JSON | YAML | Date & Time | |
|---|---|---|---|---|---|---|---|---|
| goja | no | no | no | yes | yes | no | yes* | yes |
| gopher-lua | yes | no | no | no | no | yes | yes | yes |
| otto | no | no | no | yes | yes | no | yes | yes |
| tengo | yes | yes | no** | yes | yes | no | yes | yes |
* Provided by an additional library
** Maintainers are open for idea of adding it
Remarks
goja
- Simplest to integrate.
- Too heavy - it adds 3MB to compressed binary.
- Has partial support for ECMA 2015+, but it's poorly documented which features are actually supported.
- JavaScript is a divisive language.
gopher-lua
- Using it wasn't a pleasant experience. For example, using userdata as a table froze command without any errors.
- Awful API.
- IO API is too barebone to be useful.
- Lua has some quirks, it tend to be hard to use for new developers.
otto
- Substantially harder to work with than goja.
- No support for ES2015 or later.
- Errors tend to be a little bit cryptic.
- JavaScript is a divisive language.
tengo
- Uses custom language, but it's quite nice and easy.
- Documentation could be better, but isn't the worst either.
- Has some issues with converting Golang types to Tengo, but they can be circumvented by
marshalling/unmarshalling. - Pretty good standard library.
- It's really small, it adds only 0.36MB to compressed binary.
gpython
- There is no documentation how to integrate it into golang app.
- Seems to be no longer actively maintained.
- Passing data into VM is not supported.
- Seems to be no way to extract data from a VM.
- Everybody loves python.
yaegi
- Full-blown Golang interpreter, not suitable for scripting.