On Dec 29, 2012, at 10:09 PM, Neil Toronto wrote: >> TR proved that it is applied to Foo if anything. Is TR too >> aggressive in negative positions? > > I'm almost certain it is. Sam? (Wherefore art thou, Sam?) > > I can see an argument for having overly aggressive contracts at first, before > having large test cases that demonstrate TR's implementation is almost always > sound. If these are training wheels, though, we should consider removing > them. The math library alone has at least 18k lines of TR code, it and > exercises the type system pretty thoroughly. > >> In this case, the chaperone is necessary, since the "a" means one value >> (not multiple), so you cannot eliminate the contract. Sadly. > > One asymmetry between multiple arguments and multiple return values is that > the number of arguments a procedure accepts is observable, but the number of > return values isn't. If it were observable, and TR were less aggressive with > the first `Foo', a chaperone would be unnecessary. > > There have got to be other uses for that, but I can't think of any offhand. > Something to do with continuations, maybe? But TR could easily annotate > lambdas with the number of values they return.
I have no doubt that right now we need a chaperone. I am arguing that we don't need a foo? check for the argument. _________________________ Racket Developers list: http://lists.racket-lang.org/dev
