Actively maintained production compilers for middle-age languages
The owners of the Borland C++ compiler have stopped maintaining it. So we are now down to, by my counting,
three four different production quality C++ compilers still being actively maintained (GCC, LLVM and EDG); lots of companies repackage EDG and don’t talk about it.
How many production compilers for other middle-age languages are still being actively maintained?
Fortran probably needs more than one hand to count its compilers. Nothing like having large engineering applications using the languages features supported by your compiler to keep the maintenance fees rolling in.
C still has lots of compilers (a C validation suite vendor told me many years ago that they had over 150 customers). Embedded processors can be a very tough target for the general purpose algorithms used in GCC and LLVM, so vendors with hand crafted compilers can still eek out a living.
Perl has one (which I find surprising).
R has one, but like Cobol it is not a fashionable language in compiler writing circles. Over the last couple of years there have been a few ‘play’ implementations and rumors of people creating a new production quality implementation.
Lisp has one or millions, depending on how you view dialects or there could be a million people with a different view on the identity of the 1.
There are lots of languages which have not yet reached middle-age, so its too soon to start counting how many actively supported compilers they still have in production use.