On Mon, Aug 23, 2010 at 8:58 PM, Neil Toronto <[email protected]> wrote: > > It would be nice if assert were capable of this. To do that, though, I think > the type checker would have to treat the expression after the "if" in this > case: > > (begin (if (pred? x) > <something useful> > (error ...)) > <some other useful thing...>) > > as part of the "then" branch. (And as part of the "else" branch when the > error is in the "then".)
This is something I've wanted for a while. It comes up a lot in code like this: (unless (foo? x) (error 'bad-input)) (foo-fun x) It requires some involved-but-I-hope-straightforward to the machinery of occurrence typing, but it's something I plan to add eventually. -- sam th [email protected] _________________________________________________ For list-related administrative tasks: http://lists.racket-lang.org/listinfo/users
