[racket] Constructors for sequences

On Apr 30, 2012, at 8:23 AM, Sam Tobin-Hochstadt wrote:

>> 
>> Another problem is that not all sequence types are polymorphic. For example,
>> strings are sequences, but strings can contain only characters. So what
>> would
>> 
>>  (sequence-map char->integer "abc")
>> 
>> return? Custom sequence types can add arbitrary additional constraints.
> 
> I believe that the Scala folks have handled this too.  I really
> recommend looking a what they've done.


Ryan: I am not saying that I want polymorphism in the elements of the sequence. I am calling for polymorphism in the constructor. 

Sam: since this issue appears to be particularly relevant in the context of Typed Racket, I think you should take ownership of the issue. I am sure there is a paper in this topic, single-authored or lead-authored, for you.