I am fed up with config languages where indentation matters or which require strange syntax to support a few levels of nested maps or require a manual to write a few lines of config.

I was dreaming of a config language which is as simple as JSON but also has a few niceties so it's not a pain to read/write it. This is what I came up with.

The golang implementation of the language is here: https://github.com/yuce/go-jacl The language grammar is in ANTLR4, so it should be easy to add support for other languages.

Hopefully this is useful to someone else.

According to you, what would be the differences with Dhall?

I've checked out Dhall very superficially, but it seems to be aimed at being a strict language to generate YAML and JSON, so IMO it has different goals than Jacl. E.g., an empty list is [] : List Natural in Dhall vs [] in Jacl. Dhall has A LOT of features. It looks more like a programming language than a configuration language. Since its goals are different, Dhall lacks a few features of Jacl like optional commas and underscore support in numbers. etc.