Ah, yes.  That would be the problem -- I'm still on 6.6.  Okay, time to upgrade!

My belief is that when I upgrade (on OSX) I will need to reinstall all
modules I've 'raco pkg install'd.  Is there an easy way to
automatically port them all over?

On Fri, Jan 5, 2018 at 3:24 PM, Daniel Feltey
<daniel.fel...@eecs.northwestern.edu> wrote:
> Are you using a recent version of Racket? I see the same error in Racket
> 6.8, but not in more recent releases.
>
> Dan
>
> On Fri, Jan 5, 2018 at 2:15 PM, David Storrs <david.sto...@gmail.com> wrote:
>>
>>
>> https://docs.racket-lang.org/reference/data-structure-contracts.html#%28def._%28%28lib._racket%2Fcontract%2Fprivate%2Fmisc..rkt%29._flat-contract-with-explanation%29%29
>>
>> says:
>>
>> (flat-contract-with-explanation get-explanation   [#:name name])  →
>> flat-contract?
>> get-explanation : (-> any/c (or/c boolean? (-> blame? any)))
>> name : any/c = (object-name get-explanation)
>>
>> When I try to create a contract that means "a list of length >= 2", I
>> get the following:
>>
>> (flat-contract-with-explanation
>>   (lambda (l)
>>     (cond [(and (list? l) (>= (length l) 2))]
>>     [else
>>       (lambda (blame)
>>         (raise-blame-error blame l '(expected: "list with length >=
>> 2"\ngiven: "~e" )))]))
>>          #:name 'foo)
>> ; application: procedure does not accept keyword arguments
>> ;   procedure: flat-contract-with-explanation
>>
>> What am I not understanding?
>>
>>
>> PS:  I know I could do (-> (and/c list? (lambda (l) (>= (length l)
>> 2)))) any) but I wanted to get something that wouldn't return ??? in
>> the error message
>>
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