How CUE wins

A big problem with configuration parameters is understanding what they do. Typically you depend on the documentation and experimentation, which is okay for a text editor but more difficult when software gets more complex and abstract.

To find out what a function does, you can read its definition. But the meaning of a constant or a configuration parameter doesn’t come from its definition. It comes from the code that uses it. Typically, it could be used anywhere in the program, and the code could be of arbitrary complexity.

But users typically don’t read the source code at all, so basically you’re tweaking a global variable and you hope it does what you think.

Configuration files are written in little languages where each parameter has potentially global effect and the interactions between them is usually unspecified. We hope they’re orthogonal, but this depends on the good taste of the language designer. When constants get turned into configuration parameters on an ad-hoc basis, this language is unlikely to be designed well.

But it seemed to me that Cue wanted to be in charge: I could see how to import an existing JSON or YAML file, converting it to Cue and committing it to the repo, but I could not work out how to load JSON or YAML as input data at run time.

I hope this is easier now, but when I tried it seemed to lack some basic command-line affordances that would make it usable in place of Python or jq.