Incremental compilation in Chapel

Question

I have been learning Chapel with small programs and they are working great. But as a program becomes longer, the compilation time also becomes longer. So I looked for the way to compile multiple files one by one, but not with success yet. By searching the internet, I found this and this pages, and the latter says

All of these incremental compilation features are enabled with the new --incremental flag in the Chapel compiler, which will be made available in Chapel 1.14.0 release.

Although the Chapel compiler on my computer accepts this option, it does not seem to generate any *.o (or *.a?) when compiling a file containing only a procedure (i.e. no main()). Is this because the above project is experimental...? In that case, can we expect this feature to be included in some future version of Chapel?

(Or, the word "incremental compilation" above is not what I'm expecting for usual compilers like GCC?)

My environment: Chapel-1.14.0 installed via homebrew on Mac OSX 10.11.6.

Answer 1

The Chapel implementation only fully compiles code that is used through the execution of the main() routine. As a starting foray, the incremental compilation project tried to minimize the executable difference between code compiled through normal compilation and code compiled with the --incremental flag. This was to ensure that the user would not encounter a different set of errors when developing in one mode than they would the other. As a consequence, a file containing only a procedure would not be compiled until a compilation attempt when that file/procedure was used.

The project you reference was an excellent first start but exposed many considerations to the team which we had not previously considered (including the one you have raised). We're still discussing the future direction of this feature, so it isn't entirely clear what that would entail. One possible expansion is "separate compilation", where code could be compiled into a .o or .a which could be linked to other programs. Again, though, this is still under discussion.

If you have thoughts on how this feature should develop, we would love to hear them via an issue on our Github page, or via our developers or users mailing lists.