On Wed, Jan 5, 2011 at 8:22 AM, Keiko Nakata <ke...@kurims.kyoto-u.ac.jp> wrote: >> raise just calls a handler that is the one that does the interesting >> control. > > So having separate implementations is for optimization? >
I don't think `raise' can be defined via `abort'. `raise' calls the exception handler in the current continuation. If the exception handler were installed as a continuation prompt (with a prompt handler that calls the continuation handler), `raise' could transfer control to the exception handler via `abort', but the exception handler's continuation would be wrong. I don't think you could rebuild the missing portion of the continuation by reinstalling it before calling the exception handler due to dynamic-wind frames, which could notice the exit and re-entry, and continuation barriers, which could prevent reinstallation. (Exception handlers are actually installed as continuation marks, with `raise' collecting the marks and trying them inside-out. I imagine that `raise' is implemented in C because many other C-implemented primitives need to call it, but that's just a guess.) _________________________________________________ For list-related administrative tasks: http://lists.racket-lang.org/listinfo/users
