The one that would allow a domain specialist to skip all the dev/build-ops and wheel-research into a project structure and jump straight into a business logic. Akin to what excel is to users, ignoring its clumsy parts in this analogy.

To name a few details:

Rich but plain standard library with convenience features. E.g. if you have to read json file, you just readJsonFile(filename), not sys.fs.readFile(fn, “a”, {encoding:”utf-8”}).pipe(new JsonReader({streaming:true}).inPipe()).collect(pipeUtils.buildArray()). If you have a date, it should be easy to modify, format or extract any of its parts, and it must be a built-in standard type. If you work with http, it must be result = http.postJson(data), easily findable in a reference. If you want to just communicate with another instance, it’s result = myInstance.<method>(<args>), not http.

Good data extraction, transferring and restructuring features, e.g. var data1 = obj.{name, id, contacts[].value}; obj.{a, b} = data2.

Development environment is the same as runtime, no explicit build-deploy phase. See a bug or require a new feature? Click “Menu - Edit module” and edit it right there with live data and live tests. When you save, your temporary db instance/transaction/backup/whatever is applied to the main branch, after it gets its own backup.

I have much more bullet points than time rn, so I’ll stop here.

This is not exactly a “language”, but that would be perfect.