What would be your definition of "proprietary" here?

In some ways, Java is a proprietary programming language, owned now by Oracle.

Some privative applications have custom programming language, just like some free software also have custom programming language (even if nowadays, there's a choice of re-usable embedable programming languages, some of them even standardized).

But what we can note in general, is that the "proprietary" programming languages are a PITA to use.

For example, in Objecteering (version 5), there was a scripting language named J which was horrible. For a fee, you could get one that was slightly less horrible to use too. But still.

"Happily", in Objecteering version 6, I'm told they switched to java instead, and indeed nowadays the offspring of Objecteering, Modelio, is based on eclipse and uses Java.

Two other examples coming to mind are:

- AutoCAD, with its infamous AutoLISP. Not that lisp be a bad embedded programming language, on the contrary, if you look at emacs and its emacs lisp (which is not the best of the lisps around but still let us write nice lisp programs, from the small punctual customization to whole applications (emacs has spreadsheets, web browsers, database management systems, games, IDEs, anything written in emacs lisp)), or embeddable full Common Lisp implementations such as ecl (libecl.so) or other less well known lisps provided as libraries to be embedded in applications. But amongst the lisps, AutoLISP is one of the worst. Not as bad as Gosling's MockLisp, the (pseudo) lisp that was used in Gosling's Emacs, but still bad.

- CYC and OpenCyc have a CycL lisp like language that's also quite bad, from the language point of view. It's a wonder, given the availablility of ecl, why people insist on designing their own half assed bad lisp, instead of just embedding Common Lisp. Or even scheme, there are some quite good scheme implementations that you could embed in applications...

There's of course also:

- AppleScript. What an horror! I mean, I can understand that 30 or 40 years after the COBOL experiment, they wanted to try it again to see whether they could at least design a programming language using an English subset that any non-programmer could use to script their system and applications. But this SHOULD HAVE STAYED IN THE FUCKING LABORATORY! as a clearly failed experiment.

And anything "4G" and "integrated".

I'm sorry I can't give you more examples, since as I mentionned above, it's generally a very difficult experience, I try to avoid anything related to "proprietary" programming languages, so it's difficult to have an exhaustive list.

Now we have to be careful to distinguish "proprietary" programming language, (where the purpose is to provide a "Turing-complete" programming language to write scripts or high level applications), from DSL, Domain Specific Languages, that can have notions, notations and syntaxes that may seem strange on the first look, but that are justified by the existing habits and usages of a given community of users in a given domain. You may find in application some domain specific language that may look strange but that fulfill completely the need of their users. The problem only comes when they want to have programmers use them.