At Thu, 27 Jun 2013 12:35:10 -0400, Sean Kanaley wrote: > As a more general solution to this kind of interactive debugging issue, > how difficult would implementing a typical Common Lisp REPL be? I'm > thinking of adding the kind of error/condition handler like: > > "<error or condition goes here> > > enter a number: > > 0 - enter new value > 1 - exit to top level > 2 - exit one level > 3 - print stack trace > 4 - etc. > > I'm not familiar with Racket's internals so I don't know how much this > is a REPL hack vs. rewriting the whole system (the condition system > isn't necessary)... If it's not too impossible I would be happy to make > this contribution...
Racket's implementation (and maybe to some degree, I think, its design) does not support restartable exceptions, except in the case of the `exn:break' exception. So, option 0 would be difficult or impossible to implement as a hook into the run-time system. A debugger could instrument programs to allow this kind of restart by wrapping every expression with a prompt, but I think that would be fairly expensive in the current implementation. ____________________ Racket Users list: http://lists.racket-lang.org/users
