This is already fixed at HEAD, https://github.com/plt/racket/commit/1334e8dcc77854ac826306d3f6a36150cb0bf0c1 has the fix.
On Sun, Apr 7, 2013 at 7:47 AM, Sam Tobin-Hochstadt <sa...@ccs.neu.edu> wrote: > On Sun, Apr 7, 2013 at 10:18 AM, Andrey Larionov <anlario...@gmail.com> wrote: >> Hello, Racket community. >> I'm a newbie and just started study Racket and Typed Racket and a little >> confused with generalization and inference. >> I found what inference works different for different containers type. For >> example: >> Set: >>> (set 0 195 196) >> - : (Setof Byte) >> (set 0 195 196) >> List: >>> '((195 . 1) (196 . 2)) >> - : (Listof (Pairof Positive-Byte Positive-Byte)) [generalized from (List >> (Pairof Positive-Byte One) (Pairof Positive-Byte Positive-Byte))] >> '((195 . 1) (196 . 2)) >> HashTable: >>> #hash((195 . 1) (196 . 2) (197 . 3)) >> - : (HashTable Integer Integer) >> '#hash((195 . 1) (197 . 3) (196 . 2)) > > This is because sets and lists are immutable, while hash tables are > (potentially) mutable. Typed Racket generates more general types for > mutable data because otherwise the lack of subtyping would make such > data very hard to use. > > In fact, this hash table is immutable, but Typed Racket doesn't > distinguish between mutable and immutable hash tables. If it did, > then you'd get the result you'd expect here. > >> Actually i'm writing library for msgpack protocol and decide to implement it >> in Typed Racket. Here is my code which did't type check and broke all other >> program: >> (define-type Atom (U False True Null)) >> (: atoms (HashTable Byte Atom)) >> (define atoms #hash((#xc0 . ()) >> (#xc3 . #t) >> (#xc2 . #f))) >> Error: Type Checker: Expected (HashTable Byte Atom), but got (HashTable >> Integer Atom) in: #hash((195 . #t) (194 . #f) (192 . ())) > > This is a bug. You may be able to work around it by using the `hash` > function, instead of the literal data constructor. > > Sam > ____________________ > Racket Users list: > http://lists.racket-lang.org/users ____________________ Racket Users list: http://lists.racket-lang.org/users
