On Sat, 10 Dec 2011, Sam Tobin-Hochstadt wrote:
On Sat, Dec 10, 2011 at 5:54 PM, Jeremiah Willcock <jewil...@osl.iu.edu> wrote:
When I run the following program:
#lang typed/racket
(struct: A ((f : (HashTable Any Any))))
(provide (all-defined-out))
I get the error message:
racket-Linux-install/lib/racket/collects/racket/contract/private/hash.rkt:57:0:
hash/c: expected either a flat or chaperone contract for the domain, got Any
"Check Syntax" does not produce any errors, and highlights the program
correctly. My "About DrRacket..." version string is "Welcome to DrRacket,
version 5.2.0.5--2011-06-21(-/f), english" (from the Git repository as of
Dec. 6, 2011). The "provide" form is necessary for the program to fail. I
would appreciate any help you might be able to give.
The problem is in the `Any' contract. The implementation of `Any'
can't be used as the contract for hashtable keys.
I'll fix this so that it works for this program, but you won't be able
to, in general, define a `HashTable' with key type `Any' in Typed
Racket and insert higher-order values as keys.
To work around this for the moment, use a more specific contract than
`Any' on the keys.
I've tried more specific key types as well, and got similar errors for
those as well (at least for something define-typed as (U (Vectorof Any)
Symbol)).
-- Jeremiah Willcock
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