On Sun, Jan 6, 2013 at 2:55 PM, Robby Findler <ro...@eecs.northwestern.edu> wrote: > What if you added an extra field to immutable values (ie all TR structs > would have this hidden field) such that, when they passed across a boundary, > the field got mutated to say what type it passed at. Then, when the value > passed back into TR, TR could check to see if has this secret field and what > the type was and then avoid more checking.
The problem is that this info isn't available anywhere (and I'm not sure it's really sensible). Consider the `cons` function (on lists only). If you write `(cons 'hello empty)` in untyped code, what type should get inserted, and where should that be calculated? This calculation can't really be done both automatically and correctly ahead of time, and would add a bunch more expense. Sam _________________________ Racket Developers list: http://lists.racket-lang.org/dev
