[plt-scheme] typed scheme intro

From: Robby Findler (robby at eecs.northwestern.edu)
Date: Thu Apr 8 16:21:35 EDT 2010

Ah. I see. (I didn't understand the error message, fwiw. I do now that
I know what the error is, tho... kind of.)

I changed the fields to Number and it also type checked. Maybe that's
also a good change to the example?


On Thu, Apr 8, 2010 at 3:17 PM, Sam Tobin-Hochstadt <samth at ccs.neu.edu> wrote:
> On Thu, Apr 8, 2010 at 4:15 PM, Robby Findler
> <robby at eecs.northwestern.edu> wrote:
>> What type annotations did you put, exactly? I tried changing the
>> result of mag to Number and otherwise leaving it as is (from the docs)
>> and I get this:
>> Welcome to DrScheme, version [3m].
>> Language: typed/scheme; memory limit: 512 MB.
>> . Type Checker: No function domains matched in function application:
>> Domains: Exact-Nonnegative-Integer
>>         Number
>> Arguments: Number Number
>>  in: (sqrt (sqr (pt-x p)) (sqr (pt-y p)))
> That's from the missing `+' operation.
> --
> sam th
> samth at ccs.neu.edu

Posted on the users mailing list.