An unreasonably practical update for EYG.

The text syntax for EYG is now properly documented. New filesystem effects in the CLI make useful shell scripts possible. Installing the CLI from source has its own guide

All this makes using EYG much easier and brings the goal of a "a better bash" much closer.

A text syntax for EYG

The primary mechanism for writing EYG has been the structural editor, as seen on the website. This is still a supported way of creating EYG programs. That said, there are good reasons to have a text syntax. A text parser to EYG has been part of the project, just undocumented, for a good while.

Having the text syntax but not documenting it is simply a wasted opportunity. So the simple syntax guide is now complete, covering every feature supported by the parser.

I will emphasise that both approaches are supported from now on. Also the semantics of the language are identical regardless of the approach used.

Files with the .eyg extension are text, files with .eyg.json are IR. Both can be passed to eyg run and produce the same result.

Parser errors

Now that text syntax is a fully supported part of the EYG toolchain it was a good time to improve the parser. The parser will now give meaningful errors.

error: expected a string path after `import` at position 7
hint: import paths must be string literals, e.g. `import "./module.eyg.json"`

 1 | import 42
            ^

File system effects

The CLI now implements ReadFile, WriteFile, AppendFile and ReadDirectory. Together with the existing Print and Fetch effects, this is enough to write small scripts that do real work on your computer.

The full list of effects implemented by the CLI is documented in the effects reference.

The modifying text guide shows how you can use scripts to replace use of shell tools like ls, find and grep. Full parity with these tools will likely take a few more guides but the foundation is there. Of course EYG is a nice language to work with so creating your own utility modules is a good way forward.

Binary builtins

While I was working with the latest effects I noticed that some missing builtins where making it hard to complete tasks. The builtin functions binary_size and binary_concat have been added.

CLI polish

The CLI has had a round of polish. The commands eyg help and eyg --version now do what you would expect.

Installing the CLI is explained in the install from source guide.

Under the hood

The REPL, interpreter and website all share a single implementation of module and package caching. This was a large change in how the runner worked and I'm pleased to have landed that.

Next

With the backend work to pull packages and modules completed writing useful EYG scripts is much easier. Once you are writing scripts the next step is to share them. Development priority is now to build functionality around sharing and publishing packages.

That's all for this update, I hope you have enjoyed it.

This issue is available, and shareable, at https://eyg.run/news/editions/8