specification VS Oberon

Great, thanks!

There are books online for free, e.g.

https://people.inf.ethz.ch/wirth/ProgInOberonWR.pdf

and https://ssw.jku.at/Research/Books/Oberon2.pdf

Oberon+ is a superset of Oberon 90 and Oberon-2. Here is more information: https://oberon-lang.github.io/, and here is the current language specification: https://github.com/oberon-lang/specification/blob/master/The.... I already had valuable feedback here on HN concerning the channel extensions. Further research brought me to the conclusion, that Oberon+ should support both, channels and also monitors, because even in Go, the sync package primitives are used twice as much as channels. Mutexes and condition variables can be emulated with channels (I tried my luck here: https://www.quora.com/How-can-we-emulate-mutexes-and-conditi...), but for efficiency reasons I think monitors should be directly supported in the language as well, even if it might collide with the goal of simplicity.

Feel free to comment here or e.g. in https://github.com/rochus-keller/Oberon/discussions/45.

Oberon+ already has generics and they should play well with my present proposal: https://github.com/oberon-lang/specification/blob/master/The...

> Most of the time people don't want unbounded and unknown lifetimes on the executors, but instead want to be able to see that directly in the code.

You mean something like join? This can easily be done by adding a channel on which each thread of the interesting group sends when finished. Thanks for the link, I will have a look at it.

A proc is a function with no return.

A function is a function that returns something.

Oberon+ keeps it's predecessors' idiotic distinction, but takes it one step further: both functions and procedures are decalred with `proc` or `procedure`, functions are `proc`s that have a return type.

And yet:

- procedure calls don't have to specify parameters apparently, but function calls must specify all parameters

- functions cannot be used in Oberon+'s weird exception handling. [1] You do a call with `PCALL(res, P, args)` where res is a variable that will hold the result of the exception if it happened, and P is the procedure. You cannot pass functions (aka procedures which have a return type)

As the spec so wonderfully says [2],

--- start quote ---

There are two kinds of procedures: proper procedures and function procedures. The latter are activated by a function designator as a constituent of an expression and yield a result that is an operand of the expression. Proper procedures are activated by a procedure call. A procedure is a function procedure if its formal parameters specify a result type. Each control path of a function procedure must return a value.

--- end quote ---

[1] https://github.com/oberon-lang/specification/blob/master/The...

[2] https://github.com/oberon-lang/specification/blob/master/The...

> Although the relative plethora of Oberon variants [..] suggests that maybe it was still not quite fully evolved.

That's a reasonable conclusion, but one has to consider that most variants came from academia and focused on specific scientific questions, not on the adaptation to practical needs of the industry.

> it would be possible to re-unify them under one standard, in the way that Common Lisp managed to do

I did that with Oberon+ which unifies Oberon, Oberon-07 and Oberon-2.

It also includes ideas of Component Pascal and Active Oberon (though I don't like the syntax of these two languages very much).

See https://oberon-lang.github.io/2021/07/16/comparing-oberon+-w... and https://github.com/oberon-lang/specification/blob/master/The....

> ...from the point of definition to the end of the scope..

Not sure what you mean. Is it about the fact that all variables are declared in the header of the procedure, i.e. not somewhere in the body as e.g. in C# or Java? This is actually the same with Active Oberon and Modula-3 (though the latter can have nested blocks like Ada). In case you mean that the order of declarations is relevant, Oberon+ assumes at least a two phase parser by design; a declaration sequence can contain more than one CONST, TYPE and VAR section in arbitrary order, interleaved with procedures, and the order of declaration is not relevant; see e.g. https://github.com/oberon-lang/specification/blob/master/The...

PL/SQL and Ada are powerful languages but rather complex and likely not well suited for beginner courses. Delphi is great, but actually I prefer the type-bound procedure notation introduced with Oberon-2 and also adopted by Go. The original Oberon syntax is a bit old-fashioned, but there is a more modern variant, Oberon+, which supports both the old and more modern syntax and a few more streamlined Oberon-style features, and should appeal more to the younger generations. See https://github.com/oberon-lang/specification.

Here is an example: https://oberon-lang.github.io/, see section Generic Programming; note how the modules have type parameters and how generic modules are instantiated by the import declaration in section Object Oriented Programming.

Here is the specification: https://github.com/oberon-lang/specification/blob/master/The...

Here is a discussion why it is designed like this

> Sure there's a small overhead to smart pointers

Not so small, and it has the potential to significantly speed down an application when not used wisely. Here are e.g. some measurements where the programmer used C++11 and did everything with smart pointers: https://github.com/smarr/are-we-fast-yet/issues/80#issuecomm.... There was a speed down between factor 2 and 10 compared with the C++98 implementation. Also remember that smart pointers create memory leaks when used with circular references, and there is an additional memory allocation involved with each smart pointer.

> Garbage collection has an overhead too of course

The Boehm GC is surprisingly efficient. See e.g. these measurements: https://github.com/rochus-keller/Oberon/blob/master/testcase.... The same benchmark suite as above is compared with different versions of Mono (using the generational GC) and the C code (using Boehm GC) generated with my Oberon compiler. The latter only is 20% slower than the native C++98 version, and still twice as fast as Mono 5.

Great, thanks!

There are books online for free, e.g.

https://people.inf.ethz.ch/wirth/ProgInOberonWR.pdf

and https://ssw.jku.at/Research/Books/Oberon2.pdf

Oberon+ is a superset of Oberon 90 and Oberon-2. Here is more information: https://oberon-lang.github.io/, and here is the current language specification: https://github.com/oberon-lang/specification/blob/master/The.... I already had valuable feedback here on HN concerning the channel extensions. Further research brought me to the conclusion, that Oberon+ should support both, channels and also monitors, because even in Go, the sync package primitives are used twice as much as channels. Mutexes and condition variables can be emulated with channels (I tried my luck here: https://www.quora.com/How-can-we-emulate-mutexes-and-conditi...), but for efficiency reasons I think monitors should be directly supported in the language as well, even if it might collide with the goal of simplicity.

Feel free to comment here or e.g. in https://github.com/rochus-keller/Oberon/discussions/45.

> Does anyone know why Wirth never modernized his style?

Readability. It's easier to read the source code with uppercase keywords. (I think Wirth once said that code is written once but read many times). See this source code - https://raw.githubusercontent.com/rochus-keller/OberonSystem... - to get an idea of this (the uppercase keywords allow you to easily scan the blocks of code). Ofcourse, one can claim that the same can be achieved better today with colour-coded keywords.

If I remember right, the Oberon+ IDE - https://github.com/rochus-keller/Oberon - gives you an option to disable this and use lowercase keywords.

> gain a deep understanding of it .. generate smaller subsets of the system

You can use the OberonViewer for this purpose with the original source code, or the Oberon IDE with a version of the Project Oberon System which runs with SDL on all platforms, see https://github.com/rochus-keller/oberon/#binary-versions and https://github.com/rochus-keller/OberonSystem/tree/FFI

> Regardless, which one is more likely to be ported to a different architecture in the future?

Not sure I understand the question. I'm talking about CPU architectures. The current implementation is in x86 assembler. So if you want to run it on AMD64 or ARM, then you have to replace all assembler files, in the present case probable the full source code.

> what are the comparative performance benchmarks of the low-level language versus the high-level language?

I don't have any measurements. But consider that many operating systems are implemented in C (e.g. Linux) with only isolated parts in assembler, so it is easier to port to other architectures. Linux apparently is fast enough and available for nearly every CPU. Oberon in contrast to C is garbage collected, which also affects performance. I have measurements comparing the same benchmark suite implemented in C++ and in Oberon, where the former is about 22% faster (see https://github.com/rochus-keller/Oberon/blob/master/testcase...).

I actually had a similar problem some years ago and finally moved away from LLVM because of complexity, continuous research effort and performance. My current Oberon+ implementation works like this: the CIL code generator together with Mono is used during development, integrated with the IDE, using the debugging features integrated in Mono; to deploy the application and to gain another factor 2 of performance C99 instead of CIL can be generated and compiled with any compatible toolchain. Here are some performance measurements: https://github.com/rochus-keller/Oberon/blob/master/testcases/Are-we-fast-yet/Are-we-fast-yet_results_linux.pdf. Compiling to CIL is very fast and the time Mono needs to compile and run is barely noticable.

> annoying aspects was requiring the .NET runtime ... OpenJDK is a blessed implementation in a way that Mono never was

Which is unjustified, because Mono CLR is just a single executable less than 5 MB which you can download and run without a complicated installation process (see e.g. https://github.com/rochus-keller/Oberon/#binary-versions ). AOT compilation on the other hand is a huge and complex installation depending on a lot of stuff including LLVM, and the resulting executables are not really smaller than the CLR + mscorlib + app.