Hyper compiler 0.3.33 released

I have released a new version of the compiler again, we're at 0.3.33 right now. The version number is actually increasing less fast than before I did any releases. The first private release was 0.3.26, the first public release was 0.3.29, so this is the fifth release I have done. Before I started releasing versions I also incremented the version number, but this was a lot faster than it is now. For the same amount of changes that are now in one new release, I would have probably done about 6 or 7 version increments back then. I cannot do the same thing anymore of course, it would be silly to release a new version each time I have made a couple of trivial changes.

The changes I have made in the latest version of the compiler are steps towards a working code generator. I am giving priority to the front end things that are needed by the compiler back end. The first such thing in the release of today is checking for the program entry point. This includes checking a 'begin' specification if it is present, finding the 'static procedure main' and doing the necessary checks on it. Another improvement is a basic support for constant folding, except that no folding is done at the moment, but the compiler can already use unsigned integer literals in type checking. This feature is used by another one: checking of array sizes. You can declare arrays with fixed size and the compiler will check their compatibility. And the third important change is passing of parameters that are not to be changed, i.e. 'in' parameters. They are now passed by reference and completely read-only.

The next things on my 'to do'-list are real constant folding and constructor initializer lists. I suppose those are sufficient to allow me to start working on the code generator. I still have compilation problems with the LLVM tools as I wrote in my previous blog post. I don't think this will be a problem because the compiler front end linked with LLVM works perfectly. I can still compile the official version of LLVM and use its tools on the LLVM bytecode generated by my compiler.

Another thing: I don't really get any feedback of users yet. So if you try the compiler, please let me know what you think! Tell me the things you like, not just what you don't like. I have installed a visitor counter on my website some time ago, and it seems that I do have some visitors looking around. Yay! :-)

type deduction for variables + back end progress

I have an idea for a new feature for variables: automatic type deduction. A new reserved keyword "auto" is used in place of the type for the variable, and the compiler will deduce the type from the type of the initializer expression. The type will always be a pointer or a reference, to avoid unneeded copies of the initializer.

procedure test(x : int, y : const int, z : * int)
var a : auto = x   # var a: & int = x
var b : auto = y   # var b : & const int = y
var c : auto = z   # var c : * int = z
var d : auto = a + b  # var d : & int = a + b
end

I am still working on the compiler back end. Progress is very slow, because I don't have much time to work on it. I got most of the LLVM libraries compiled with CMake (LLVM normally uses GNU autotools), and linked with my front end. The front end currently emits a simple hello world program as LLVM assembly code (regardless of what sourcefile you 'compile'). I did not get the LLVM tools compiled yet; for "llc" I am stuck on a link error about some symbols from libtool. I have never used libtool myself so I don't know how it's used in a program. I will have to take another look and if I can't solve it I will have to ask for some help on the CMake mailing list. I wonder why my compiler gets linked with LLVM without errors and why "llc" fails. Other work in this matter is on the front end. There is some functionality that is needed for code generation that is still missing in the front end. For example, I still need to finish constant folding, because this is required for determining the size of array types. After that I can start implementing real code generation.

Hyper compiler 0.3.32 released

Today I have released a new version of the compiler. The most important new thing is support for the new namespace system. This means that finally all example programs are accepted by the compiler, including the new Hello World! Imports are not yet really supported; imports of user-defined sourcefiles are ignored, and the only allowed standard library import is the import of 'system.stdio'. The new compiler now also supports chained comparison operators, so you can now use code like:

if x = y = z then
# TODO : implement this
end

Another nice thing to have is that the compiler will generate a warning by default for this code. Something like:

file.hyp:3:2: warning: TODO: implement this

The compiler will actually notice 'TODO' or 'FIXME' in comments and generate warnings for them. In my opinion warnings provide useful information so they are enabled by default. But you can turn them off individually if you like with a commandline switch like "-W-no-todo".

As you can see the compiler still isn't at version 0.4.0 yet. Well, I have chosen for a different approach. I will keep releasing the front end of the compiler as I am doing now, and I will develop a version of the compiler with LLVM back end in parallel. The version 0.4.0 will be given to a release that marks an important event for the front end; maybe when I am ready to start the implementation of more advanced things like inheritance. I do not plan to release the version-with-back-end to the website soon because it will be completely unusable until some time in the future. And if no one cares anyway, then why bother releasing it?

progress...

It's been a while since I wrote something the last time. But I have made progress since then.

First of all, the Hello world example has changed again. Here is the new (and hopefully final) version:

import system.stdio

class Hello
 static procedure main()
  system.Out.line("Hello, World!")
 end
end

The 'StdIO' class has been replaced by 'Out', which will provide simple console output. The 'printLn' procedures have been renamed to 'line'.

Implementation of the compiler is now much further. The compiler on SVN trunk now supports the new namespace system, and supports importing 'system.stdio'. This means that all sample programs in the directory tests/programs now compile successfully. A new fun feature is that the compiler detects TODO and FIXME in comments and emits warnings for them. Of course new compiler options are provided to turn these warnings off, but they are enabled by default.

The compiler has been restructured internally as well. I have completed 3 major refactorings. But this is not the end of the road, much other improvements will be done in the future.

There is a good chance that the next release of the compiler will have version number 0.4.0 because of all the improvements that have been done. The milestone for 0.4.0 will then be "front-end mature enough to start implementing the back-end".

I have also created a new SVN branch where I will start to work on the compiler back-end. As said earlier I will use LLVM for this. I have imported LLVM 1.9 into the branch. The first thing to do is to get LLVM compiled with CMake, as the LLVM developers use GNU autotools to build it. But I don't, I use CMake for the front-end. Then I will try to get the Hello World program compiled with it.

Today I have written a bunch of docs again. You can find class references for the built-in types on the website.

I currently use Subversion, but I am thinking about switching to Bazaar.