On Jul 13, 2014, at 8:23 PM, Sam Tobin-Hochstadt <sa...@cs.indiana.edu> wrote:
> Probably, what's going on here is that `for/last` has a hidden loop > variable that starts off as `#f` and Typed Racket infers that to have > type `False`. I thought that was the whole point of adding the : (U Index #f), right? To provide a type for that loop variable? > > If that's the case, there's nothing you can really do other than > rewrite this as `for/fold`. Well, I tried to use for/fold, but it kept telling me to add more type annotations even when I had annotated every little thing that I could. Then I tried reversing the sequences and using for/first (which would work for what I’m doing but not in general), but if I remember correctly that seemed to have the same problem. Then I tried using the reversed sequences with for/or instead of for/first and that worked fine. But If there’s a hidden loop variable starting of as `#f`, then for/or should have the same problem, but for/or works fine. > > Sam > > On Sun, Jul 13, 2014 at 7:57 PM, Alexander D. Knauth > <alexan...@knauth.org> wrote: >> For some reason this: >> (for/last : (U Index #f) >> ([i : Index (ann (in-range 5) (Sequenceof Index))]) >> i) >> Is giving me this error: >> . Type Checker: type mismatch >> expected: False >> given: Index in: (for/last : (U Index #f) ((i : Index (ann (in-range 5) >> (Sequenceof Index)))) i) >> >> Why is it expecting False? >> And is there some type annotation I can put somewhere to fix it or anything? >> >> >> ____________________ >> Racket Users list: >> http://lists.racket-lang.org/users ____________________ Racket Users list: http://lists.racket-lang.org/users
