Survey on map/flatMap disambiguation

Remi Forax forax at
Tue Mar 19 08:38:27 PDT 2013

On 03/19/2013 04:22 PM, Brian Goetz wrote:
> Thanks for writing up your concerns all in one place.
>> 1. Performance gotchas?
> Of these, I think this is the worst of the concerns.  However, I also 
> think its not as bad as it sounds.  When a user hits ctrl-space in the 
> IDE, they'll see (close to each other) all the mapToXxx forms, which 
> has actually a lot of educational value. [1]
> Secondly, while boxed performance is definitely much worse than 
> non-boxed, for small streams (and most collections are small), it 
> might not make a difference anyway.  I've definitely had the 
> experience many many times of discovering "egregious" performance 
> "bugs" like this that turned out to have no effect on actual 
> business-relevant performance metrics, because all the cost was in the 
> { XML parsing, database access, network latency, crypto, etc }.  For 
> those cases where it does make a difference, profiling will disclose 
> this immediately.  So its a gotcha, but not a disaster.
> So I think its a gotcha but nothing so bad that this makes the 
> difference for me. 

so we should remove the specialized streams because they not worth their 


More information about the lambda-libs-spec-experts mailing list