On Tue, Jun 26, 2012 at 7:26 AM, Adolfo Pérez Álvarez <adolfo...@gmail.com> wrote: > Hi All, > > It seems that the problem is in for*/list: itself. For example, the > following code fails to typecheck, but I don't see anything wrong with > it: > > #lang typed/racket > > (for*/list: ([a : Number '(1 2 3)] > [b : Number '(4 5 6)]) > (+ a b)) > > Any idea of why doesn't typecheck? I'm totally lost now ...
Looking at this smaller example, I think that the nested recursion in expansion of `for*/list` is confusing Typed Racket. I'll look into why that is, and if it can be fixed. In the meantime, you ought to be able to rewrite the loop to use `for/fold:` and `reverse` to work around this issue. Sam > > Thanks. > 2012/6/25 Adolfo Pérez Álvarez <adolfo...@gmail.com>: >> Oh my ... I mis-annotated the code *again* :-( >> >> Here is the corrected definition of colorize: >> >> (: colorize : Map (Listof Color) -> (Listof Solution)) >> (define (colorize map colors) >> (for/fold: ([solutions : (Listof Solution) empty-solution]) ([entry >> : Map map]) >> (match-let ([(cons region neighbours) entry]) >> (for*/list: ([s : Solution solutions] >> [c : Color colors] >> #:when (not (findf (λ: ([rc : (Pair Region Color)]) >> (and (memv (car rc) neighbours) >> (eqv? (cdr rc) c))) >> s)) ) >> (cons (cons region c) s))))) >> >> 2012/6/25 Adolfo Pérez Álvarez <adolfo...@gmail.com>: >>> Thanks a lot for your answer, Sam. It seems I completely missed the >>> for/xxx: forms while looking up the documentation. >>> >>>> One, as the error message said, Typed Racket needed more help in the >>>> form of annotations to check your program. Two, you were using >>>> `for*/list` as if it was `for*/fold`. Unfortunately, the >>> >>> Sorry to inform you that your version doesn't work as expected ;-) I >>> use for*/list to generate 'n' new partial solutions for each one of >>> the 's' generated by the outer for/fold for each color (it's is a >>> quick and dirty solution to the map coloring problem). So the inner >>> for/fold: doesn't do the trick :-). >>> >>> Anyway, I got the type annotations completely wrong ... by mistake I >>> defined a set of solutions as a (Listof (Pair Region Color)) instead >>> of a (Listof (Listof (Pair Region Color))). Also, I should have called >>> "empty-solution" "empty-solutions" or "empty-solution-set" instead. >>> >>> Now I've tried to use for*/list:, annotating the bindings (correctly I >>> hope), but still doesn't work. It fails (again) with the same error >>> message: >>> >>> Type Checker: Error in macro expansion -- insufficient type >>> information to typecheck. please add more type annotations in: >>> (for*/list: ((s : (Listof (Pair Region Color)) solutions) (c : (Listof >>> Color) colors) #:when (not (findf (λ: ((rc : (Pair Region Color))) >>> (and (memv (car rc) neighbours) (eqv? (cdr rc) c))) s))) (cons (cons >>> region c) s)) >>> >>> To make things a little clearer I've added a new type "Solution"; now >>> the code looks like this: >>> >>> #lang typed/racket >>> >>> (define-type Region Number) >>> (define-type Color Number) >>> (define-type Solution (Listof (Pair Region Color))) >>> >>> (: empty-solution : (Listof Solution)) >>> (define empty-solution '(())) >>> >>> (define-type Map (Listof (Pair Region (List Region)))) >>> >>> (: colorize : Map (Listof Color) -> (Listof Solution)) >>> (define (colorize map colors) >>> (for/fold: ([solutions : (Listof Solution) empty-solution]) ([entry >>> : Map map]) >>> (match-let ([(cons region neighbours) entry]) >>> (for*/list: ([s : Solution solutions] >>> [c : (Listof Color) colors] >>> #:when (not (findf (λ: ([rc : (Pair Region Color)]) >>> (and (memv (car rc) neighbours) >>> (eqv? (cdr rc) c))) >>> s)) ) >>> (cons (cons region c) s))))) >>> >>> And again, thanks a lot for your answer. ____________________ Racket Users list: http://lists.racket-lang.org/users
