Why does Anvil use a REST API?

Anvil is inspired by Rob Pike's Acme editor. One of the things that Acme provides is an API that is exposed as a filesystem. The editor's state can be read and changed by reading and writing to files. This is a great way to provide an API for a few reasons.

Extending Acme means running a separate process that interacts with Acme through the filesystem. Since the extending program is a separate process, any bugs such as poor performance or crashes are limited to that process rather than affecting the Acme process itself. This is in contrast to approaches where the editor provides a scripting language that is hosted in the editor itself, or where the editor loads compiled plugin code into it's process, which can both suffer from bugs in the extending program.

As well, since filesystem access is such a fundamental operation, no special library is needed and any programming language can be used to write extensions, including shell scripts. Extending Acme is accessible since users can write in whatever language they are most comfortable in, or choose the language that is most convenient to solve the problem.

However, providing a filesystem API is not trivial. While I'd love to have something like this for Anvil, I instead comprimised by providing a REST API. Though it is not as convenient as providing a filesystem, I hope it has much of the value. Most languages provide standard libraries to communicate with HTTP servers, and REST operations are ubiquitous and simple enough to make using such an API convenient.

You can even use it through shell scripts, via curl for example.