Author here.
> This seems to be more a simple programming language than a shell.
Currently it's only a programming language. The interactive part will be implemented in the NGS language itself.
> simple programming language
Since simple is relative: NGS is simpler than Java and more complex than awk I would say. NGS has exceptions, types with inheritance, multiple dispatch, guards (additional conditions to invoke a method), basic functional programming support, patterns, (new, in progress) facility for deeply nested data manipulation, automatic parsing of command line arguments when invoking the optional main(), threads, domain-specific syntax and facilities for running external programs and file manipulation.
Simplicity is one of the language goals but not over expressive power.
> A shell is first and foremost a UI, only secondarily a scripting language...
I'm having hard time to agree or disagree. There is a lot of interactive usage but there are also a lot of scripts in bash. When I see the scripts I wish bash was "more of a programming language".
> foremost a UI
... where surprisingly little innovation happened over the last decades. It's like in the movies when there is an object in the center of the screen and the whole world is rapidly changing around it. That object is the shell. My plans for UI are at https://github.com/ngs-lang/ngs/wiki/UI-Design .
> easily take a series of commands you'd do manually and put them in a script
You can do it in NGS and even in this simplest use case it will be better than bash - in case of an error the execution will stop (like with -e in bash) and NGS will print stack trace (which I don't know how to do in bash and not sure it can be done in a sane manner).
Edit: $a will expand to exactly one argument (as opposed to zero or more), rm -rf "$mydir/" will throw exception if mydir is undefined. Typical things which are expected from modern programming languages.
NGS uses small subset of syntax from bash so running external programs in the simple forms looks the same.